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Dr. Brown, Co-Chair of the Workgroup Writing Committee, is Associate Professor in Nursing and Nutrition, University at Buffalo, The State University of New York, Buffalo, NY.
Dr. Byers, Co-Chair of the Workgroup Writing Committee, is Professor, Preventive Medicine, University of Colorado School of Medicine, Denver, CO.
Mr. Thompson, Co-Chair of the Workgroup Writing Committee, is a cancer survivor and President, GroupBenefica, Inc., Tampa, FL.
Ms. Eldridge, Workgroup Report Coordinator, is a Clinical Research Associate at the University of Colorado School of Medicine, Denver, CO.
Ms. Doyle is Director, Nutrition and Physical Activity, American Cancer Society, Atlanta, GA.
Ms. Williams is Manager, Nutrition and Physical Activity, American Cancer Society, Atlanta, GA.
| ABSTRACT |
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This report looks at the different phases of cancer survivorship, from active treatment to advanced disease, and presents existing evidence from which informed decisions can be made regarding dietary choices. Popular complementary and alternative methods related to dietary intervention are reviewed. Nutrition information is also provided according to common cancer sites.
As this is an area that requires survivors and health care providers to communicate effectively, a special section on "frequently asked questions" is provided for use as a patient education handout.
| INTRODUCTION |
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Cancer survivors often receive dietary advice from family, friends, and health care providers, as well as from the media, health food stores, and the nutritional supplement industry. Magazine articles, books, Internet postings, family, and friends present cancer survivors with a wide range of options and choices about what to eat, how to exercise, and what types of supplements or herbal remedies might improve the outcome of standard cancer therapy.
| Workgroup Members Abby Bloch, PhD, RD, FADA Keith Block, MD Georgia Decker, MS, RN, CS-ANP, AOCN Kevin Keane Esther Fussell, MEd Kathryn Hamilton, MA, RD, CDN Ervin Hawrylewicz, PhD Lawrence Kushi, ScD Kay Makar, MPH, RD, CDN Connie Mobley, PhD, MS, RD Marion Nestle, PhD, MPH Dennis OHara Patricia Painter, PhD Cheryl Rock, PhD, RD Keren Stronach, MPH
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In addition, claims abound on the use of dietary and nutritional or herbal supplements as alternatives to standard therapy. This advice is often conflicting, making informed choices difficult. What is the cancer survivor to believe? How are general recommendations to be reconciled with the individuals immediate and long-term needs? On what basis are these important informed decisions to be made?
Nutrition and physical activity guidelines for the prevention of cancer have been established by the American Cancer Society (ACS) and are now widely used.2 The goal of the prevention guidelines is to reduce cancer incidence. In contrast, the information presented in this article is intended for both cancer survivors and those who care for them, including health care providers, families, and friends, through all phases of cancer survival.
This report presents and discusses both the scientific evidence and the im-portant practical issues that should be considered in helping patients make informed choices.
This compilation and review of information from numerous sources is intended to facilitate informed decision-making on a wide range of issues and choices about foods, physical activity, nutritional supplements, and nutritional complementary and alternative therapies. This is not a comprehensive review on the effects of nutrition and physical activity in people who have been diagnosed with and treated for cancer, nor is it a guideline of specific recommendations. It does not cover medical issues in nutrition and metabolism, such as parenteral nutrition, calculations of nutritional needs in specific medical situations, and selection of specific diets that may be prescribed for hospital inpatients.
Rather, this report presents and discusses both the scientific evidence and the important practical issues that should be considered in helping patients make informed choices about their nutrition and physical activity practices after a cancer diagnosis.
It is very important for patients to consider the nutritional and physical activity issues discussed in this document in the context of their overall medical and wellness situation. For example, although we present nutritional suggestions for patients with nausea or fatigue, we recognize that other medical interventions are likely to have a greater impact on these symptoms. In writing these suggestions, we have assumed that the patient is already receiving appropriate medical and nursing care, and is seeking information on self-care strategies to relieve symptoms and enhance health and quality of life.
Decision-Making in Uncertainty
One of the most devastating effects of cancer is a profound sense of loss of control. Behavioral research has clearly shown that those who have higher levels of self-efficacy generally feel better and function better than do those who feel they have lost control over their situation.3 Seeking ones own course of treatment and disease management, as well as confidently choosing the best course of action for oneself, is extremely important for enhancing quality of life. With so many important questions related to the challenges of cancer survivorship, and with an inadequate scientific basis for many of even the simplest questions, cancer survivors and those who care for them desperately need a credible framework of accurate information. This article provides such a framework.
When there is ample scientific evidence on an issue, choices can be easy. In contrast, when scientific evidence is insufficient, choices are difficult. Currently, there are many gaps and inconsistencies in the scientific evidence on the effects of nutrition and physical activity after cancer diagnosis.
For many of the most important nutrition and physical activity questions faced by cancer survivors, the scientific evidence comes only from in vitro and laboratory animal data, or anecdotal reports from poorly designed clinical studies. Moreover, the findings from these studies are often contradictory. Very few controlled clinical trials have been done to test the impact of diet, nutritional supplements, or nutritional complementary methods on cancer outcomes among cancer survivors. Only a few observational epidemiologic studies have examined the relationship between nutritional factors and cancer outcomes.
Properly controlled studies of the effects of nutritional and physical activity interventions on the prognosis and quality of life of cancer survivors are urgently needed, and should be a high priority for all academic and research funding agencies.
The state of the scientific evidence regarding the effects of nutritional factors on the clinical outcomes among cancer survivors is not sufficient at this time to support a set of firm guidelines for cancer survivors. There is sufficient information, however, to serve as a basis for a framework for reasonable informed choices.
| NUTRITIONAL ISSUES DURING THE PHASES OF CANCER SURVIVAL |
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Adequate dietary intake can improve the nutritional status of nearly all cancer survivors. During all the phases of cancer survival, even for cancer survivors with no apparent nutritional problems, the principles outlined in the ACs Guidelines on Diet, Nutrition, and Cancer Prevention2 should be regarded as the basis for a healthy diet (Table 1
). The ACS dietary guidelines are quite similar to those recommended by several other organizations, agencies, and experts as a reasonable basis for the dietary prevention of other chronic diseases as well as cancer.4–7 There are many special nutritional issues and needs during the phases of cancer survival, however, not specifically addressed by the cancer prevention guidelines that are addressed in this report.
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Food Choices
Cancer treatment may interfere with the ability to eat, digest, or absorb food due to side effects such as nausea, vomiting, changes in taste or smell, loss of appetite, or bowel changes. When these problems occur, usual food choices and eating patterns may need to be temporarily adjusted. For example, small, frequent meals or snacks may be easier to tolerate than are three large daily meals. Food choices during this time should be easy to chew, swallow, digest, and absorb and should be appealing, even if they are also high in calories or fat.8–11
During active cancer treatment, maintaining caloric balance is the most important nutritional goal. If it is not possible to meet nutritional needs through regular diet alone, nutritious snacks or drinks may be advisable. Commercially prepared liquid nutritional products (e.g., Boost,® Ensure,® Resource,® or NuBasics®) can also be helpful to assist with intake of calories and nutrients. These products are best used as only temporary aids.
Even though cancer treatment can cause fatigue, light, regular physical activity during treatment should be encouraged to improve appetite, stimulate digestion, prevent constipation, maintain energy level and muscle mass, and provide relaxation or stress reduction. Advice from a nutritionally qualified health care provider can be helpful in assessing problems with eating and physical activity and in creating an individualized plan to meet the specific challenges faced during the cancer treatment phase.
Nutritional Supplements
The use of nutritional supplements is a topic of considerable controversy, especially in the cancer treatment phase. It is counterproductive for patients to take vitamin supplements that contain high levels of folic acid, or to eat fortified food products that contain high levels of folic acid when using chemotherapy agents, such as methotrexate, that act by interfering with folic acid metabolism. This interaction illustrates the importance of asking and advising survivors about supplement use during treatment. Moderate amounts of foods such as breakfast cereals that do not exceed the Dietary Reference Intake established by the National Academy of Science (formerly known as the Recommended Daily Allowance) for folate are unlikely to reduce efficacy of these drugs.
Many vitamin supplements contain higher levels of antioxidants, such as vitamins C and E, than the Dietary Reference Intakes.12–16 Other dietary supplements may contain high levels of non-vitamin antioxidant phytochemicals or antioxidant minerals. Since free radicals are involved in carcinogenesis and since some epidemiologic and laboratory studies have suggested that certain antioxidants may reduce cancer risk, some survivors and clinicians might conclude that antioxidants are effective in preventing cancer recurrence. However, oxidative damage is involved in the cytotoxic actions of radiotherapy and several classes of chemotherapy agents. Taking antioxidant vitamins during chemotherapy or radiation therapy might therefore reduce the effectiveness of those therapies,17 and some experts have therefore recommended against taking antioxidant supplements during such treatment.18
Others, though, have pointed out that the possible harm of supplements is only hypothetical, and that there might be a net benefit from supplements that could help protect normal cells from the collateral damage associated with these therapies.19–21 Even endogenous antioxidants, such as melatonin, might work to enhance chemotherapy,22 but such findings have not consistently been reproduced.23 Unfortunately, this is one of the many critical questions without a good answer at this time. Therefore, it would be prudent to advise patients undergoing chemotherapy or radiotherapy not to exceed the upper intake limits of the Dietary Reference Intakes for vitamin supplements and to avoid other nutritional supplements that contain antioxidant compounds.12–23
Phase 2: Recovery From Treatment
After treatment is completed, the nutrition and physical activity plan should help rebuild muscle strength, and correct problems such as anemia or impaired organ functioning. Ad-equate food intake and physical activity are crucial to the recovery phase.8–11
Sometimes, cancer treatment causes long-term problems, such as dysphagia, xerostomia, or malabsorption, that can make eating difficult and that can impair nutritional status, leading to persistent weight loss, muscle wasting, and nutrient deficiencies.
During this phase, survivors need a nutritionally balanced diet sufficient in caloric intake and sufficiently varied to provide adequate micronutrients (as specified in the ACS Guidelines for Diet, Nutrition and Cancer Prevention).2
Recovery also requires physical activity to rebuild muscle strength. Cancer survivors with treatment-related complications or any other disabilities that interfere with diet and physical activity should be referred as needed to the appropriate health care provider to establish nutritional and activity goals.
Phase 3: Preventing Cancer Recurrence, Second Primary Cancers, and Nutrition-Related Disease
In general, there has been very little research on the nutritional factors that influence cancer recurrence. In the absence of such data, it seems reasonable, though, to recommend that cancer survivors follow carefully the guidelines for prevention defined by the ACS and others.2,4–7 The same factors that increase cancer incidence might also be important in promoting cancer recurrence after treatment. Data are most compelling for breast cancer, where the risk of recurrence might be increased by obesity and by diets high in fat and low in fruits and vegetables (see also section on breast cancer). Prostate cancer recurrence might also be increased by high saturated fat intake, or reduced by micronutrient supplementation (see also section on prostate cancer).
In addition to the risk of recurrence of the primary cancer, survivors can be at increased risk for second primary cancers, either at the same site (e.g., contralateral breast cancer) or at other sites (e.g., lung cancer after oral cancer). In addition to following guidelines for increased screening, chemoprevention, or surgical prevention for very high-risk second primaries (e.g., ovarian cancer following breast cancer in familial syndromes), following the ACS Guidelines for Diet and Cancer Prevention may be the most effective method for preventing the growth of second primary cancers.2
Phase 4: Living With Advanced Cancer
Nutrition is an important factor in establishing and maintaining a sense of well being and quality of life in survivors with advanced cancer. Although advanced cancer is often accompanied by substantial weight loss, malnutrition and weight loss are not inevitable. 8–11
In addition to adapting food choices and eating patterns to meet changing nutritional needs, effective management of symptoms and side effects, such as pain, constipation, and loss of appetite, can help promote optimal nutrition support.24 Various medications and physical activity can help to increase appetite,25 and, if needed, nutritional support can be provided in other ways for those who cannot eat enough.26,27
| SPECIFIC NUTRITIONAL ISSUES FOR CANCER SURVIVORS |
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Body Weight Changes
Cancer survivors may gain or lose body weight during treatment and recovery. Any weight loss prior to or during treatment may adversely affect nutritional well-being. Even though there are health risks related to obesity32 and even though newly diagnosed cancer patients are often strongly motivated to begin healthy habits, intentional weight loss during cancer treatment is not recommended. Weight reduction should only be attempted after the active treatment and recovery phases are complete.
Cancer and its treatment can place extra demands on the body, greatly increasing nutrient and caloric needs. Studies of protein metabolism in cancer patients have shown elevations of whole-body protein turnover and skeletal muscle wasting.33,34
Weight loss can contribute to fatigue, delay and lengthen recovery, and adversely affect quality of life.35 The line between healthy and unhealthy weight loss can be difficult to recognize for both survivors and health care professionals. All survivors, even those who are overweight, should be advised to maintain their weight during therapy. Whether overweight survivors who experience treatment-related weight gain worsen their prognosis as a result of that weight gain is unknown.
Some cancer survivors, especially breast cancer survivors, may gain weight during and after treatment. Menopausal status, nodal status, and the type, duration, and intensity of treatment influence such weight gains.36 In these situations, a healthy eating plan that meets, but does not exceed, caloric needs is advisable, along with increased physical activity. Even moderate physical activity can lead to an improved sense of well-being, improved strength, and weight stabilization in times of stress.
Maintaining body weight within healthy ranges may help reduce risks of a variety of chronic diseases including coronary heart disease and diabetes, as well as cancer.2,32
Healthy weight loss is best initiated after the recovery phase. Obesity has been associated with both increased risk and poorer prognosis of cancers of the breast and colon.37–43
Dietary Fats
Most of the interest in the relationship between low-fat diets and cancer has focused on the role of fat in the etiology and prevention of breast, colorectal, and prostate cancers. The evidence that total fat intake is a cause of breast cancer is quite weak and inconsistent,36 whereas the evidence for a role of dietary fat in the cause of colon and prostate cancers is stronger.44,45 For these latter cancer sites, though, consumption of red meats and fat from animal sources may increase risk more than total fats or fats from vegetable oils.
For prevention of heart disease, reducing consumption of saturated fats from animal foods is more important than reducing total fats in the diet. While low-fat diets have not specifically been shown to be helpful in either treating cancer or preventing recurrence, it is important to note that there have been few studies of this question.
Consumption of red meats and fat from animal sources may increase risk more than total fats or fats from vegetable oils.
Several studies designed to assess the role of diet as a cause of breast cancer have been extended to examine survival after diagnosis as related to diet before diagnosis. These studies suggest that women on lower fat diets before diagnosis tend to have less aggressive cancers than do those on high fat diets.41–43,46–60 Thus, although dietary fats might have little to do with breast cancer prevention, the levels of fat in the diet might somehow affect the growth of breast cancers that do develop.61,62
There are now two randomized trials underway testing the effects of low-fat diets on recurrence and survival from breast cancer [the Womens Intervention Nutrition Study (WINS) and the Womens Healthy Eating and Living (WHEL) Study].63 It is hoped that more direct evidence regarding the impact of low-fat dietary patterns on breast cancer recurrence and survival will eventually emerge from these two trials. While no specific recommendations regarding low-fat diets in the management of cancer can be made at this time, if individuals and their families choose to follow very low-fat regimens (about 20% of calories from fat), they should ensure that the diets are nutritionally balanced, contain essential fat-soluble vitamins (e.g., vitamins A, D, E, and K), and are adequate in calories to maintain a healthy body weight.
Fruits and Vegetables
Fruits and vegetables seem to be strongly associated with a lower incidence of colorectal and lung cancers, as well as several other common cancers.2,4–6,64–70 A diet high in fruits and vegetables might therefore also be beneficial for improving cancer survival, though there are few studies that have examined this question.
The WHEL Study, which is currently in progress, is testing the effect of a diet high in vegetables, fruit, fiber, and low in fat on survival of women diagnosed with early-stage breast cancer.63 The average participant in the study will be followed for six years, so results from this study are expected to be known by the end of 2004.
The benefits of eating fruits and vegetables might be much greater than are the effects of any of the vitamins they contain, as it is quite likely that the various vitamins and other phytochemicals in these whole foods act in synergy to reduce cancer risk.68
In the absence of clinical trials, it is reasonable for cancer survivors to adopt the general dietary recommendations issued by many different agencies, namely, to eat at least five servings of fruits and vegetables—fresh, canned, frozen, or juiced—each day.2,4–6 A serving size of fruit or vegetable is defined as: 1/2 cup of cooked vegetables or chopped fruit, 1/4 cup dried fruit, one piece of fresh fruit, one cup of raw green leafy vegetables, or equivalent amounts from multi-ingredient foods. Veget-ables and fruits are low in fat, contribute fiber and micronutrients, and are generally more healthful than many other food choices.
Physical Activity
Before beginning any program of exercise or physical activity, cancer survivors should undergo a complete health assessment to develop an individualized plan that maximizes the benefits of physical activity while reducing risks of injury.
Regular physical activity is associated with reduced risk of colorectal cancer, coronary heart disease, osteoporosis, and diabetes mellitus,71,72 and may be beneficial for the prevention of other cancers as well, including breast cancer.71–73
The impact of physical activity on the prognoses of people with cancer is less clear.74–77 Physical activity levels tend to decrease after cancer diagnosis and treatment, but increased levels of physical activity can improve overall quality of life, and result in less fatigue, lower levels of anxiety, increased energy, and a renewed sense of vitality.78–94 Increased physical activity has been shown to have beneficial effects on heart rate, lean body mass, and respiratory capacity among cancer survivors, effects that are similar to those observed in individuals without cancer.78 Thus, consistent with other recommendations regarding regular physical activity, cancer survivors and their family members should be encouraged to engage in moderate regular physical activity.
There have been only a few studies of the effect of physical activity on survival of people with cancer, and most involve only small numbers of subjects.78 Researchers in this emerging field have not been able to determine whether activity can prevent recurrence of cancer or slow the progression of disease, but studies have shown that regular physical activity can reduce anxiety and depression, improve mood, boost self esteem, and reduce symptoms of fatigue, nausea, pain, and diarrhea.79–94 These benefits can be gained through participation in moderate physical activity on most, if not all days of the week.
Moderate activities are activities that make a person breathe as hard as they would during a brisk walk. Activities such as walking, biking, and swimming are considered of moderate intensity, as well as activities such as yard work and brisk house cleaning. Ideally, at least 30 minutes of activity should be accumulated each day.
Cancer survivors can find many ways to incorporate physical activity into their daily lives. Parking further away from a destination and using stairs instead of elevators are easy ways to be more active throughout the day. A little bit of physical movement is far better than none.
Additional benefits can be gained through progressively greater amounts of physical activity. In choosing a level of activity, it is important to take into consideration the cancer survivors physical functioning and previous levels of activity.
If the disease and/or treatment results in confinement to bed rest, physical therapy in bed should be initiated to maintain strength and range of motion of joints. Prolonged bed rest can result in reduced fitness, reduced endurance, and decreased muscle strength, all of which can increase the effort required for performing daily activities. Physical activity for cancer survivors who are confined to bed, even those with advanced cancer, can help counteract the fatigue spiral and feelings of low energy that some experience under those circumstances. Even modest levels of physical activity can help maintain mobility, relieve muscle tension, and provide a mental and emotional boost.
Physical activity during cancer recovery should be individualized, initiated slowly, and progress gradually. Individuals with disabilities are encouraged to seek out specialists (e.g., physiatrists and physical therapists) to assist in developing an individualized program of physical activity.
It is especially important to ensure that adequate hydration and electrolyte balance are maintained during exercise.
Some situations or conditions may limit the ability of cancer survivors to be active. For instance, some cancers can cause electrolyte imbalances and deplete the body of fluids. In these situations, it is especially important to ensure that adequate hydration and electrolyte balance are maintained during exercise.
Survivors with metastasis to the bone, or with bone loss due to therapy, should be careful to prevent bone fractures by avoiding activities that involve jumping or twisting the hips. Survivors with chemotherapy-induced neuropathy that affects their balance should be careful to exercise in ways that avoid the risk of falls.
Many community programs provide physical activity programs for people with special needs. Programs that are designed for individuals beginning or resuming physical activity should be recommended as a starting point. As the level of physical activity improves, more challenging programs can be tolerated. Survivors who wish to participate in more intense or vigorous programs, or in high level sports, should be evaluated on an individual basis by an exercise specialist and health care provider.
Alcohol
Alcohol can be irritating to patients with oral and esophageal mucositis and can exacerbate that condition. It therefore seems reasonable to recommend that alcohol intake should be avoided or limited among patients with mucositis and among those starting head and neck radiotherapy and/or chemotherapeutic regimens that put them at risk for mucositis. Alcohol should also be avoided during chemotherapy with methotrexate and other agents that may cause hepatotoxicity.
While there is substantial evidence that alcohol may increase the risk of developing several cancers (such as cancers of the head and neck, liver, and breast),2 there is less evidence related to alcohol and survival from cancer. Alcohol increases the risk of cancers of the head and neck and liver mostly because of tissue damage that results from high levels of alcohol intake and, for the former site, a synergistic interaction with tobacco.
There is little reason to believe that the levels of alcohol use that are sufficient to reduce the risk of heart disease—i.e., one drink per day—will affect the risk of recurrence of cancers of the head and neck or liver. [One alcoholic drink is equal to 5 oz. of red or white wine, 12 oz. of beer, 1 oz. of hard liquor.] However, epithelial carcinogenesis in head and neck cancers involves a field effect, and multiple synchronous or metachronous primary lesions are not uncommon. Since survivors with upper aerodigestive carcinomas might be especially prone to new primary lesions, it could be considered prudent to suggest that they avoid regular alcohol use, if they drink at all. For cancer survivors who have previously had problems controlling their intake of alcohol, however, total abstinence is the best choice.
Increased risk of breast cancer has been shown to occur at doses as low as one to two drinks per day.36 The mechanism for this effect is not known, but may be related to the effects of alcohol on estrogen levels in women.36 If this is true, then alcohol intake, even in low doses, might have adverse effects on the prognosis of breast cancer, especially for women with hormone-responsive tumors.
Alcoholic beverages supply calories, but few nutrients. Thus, people who drink heavily may be substituting alcohol for nutrient-rich foods. This is a concern for the cancer survivor, who may have increased nutritional needs.
There has been some interest in the role of antioxidant flavonoids that exist in red wine95 for decreasing risk of heart disease or certain cancers.96–98 At this point, the effects of these factors on cancer risk or in enhancing survival after cancer are unknown. These beneficial phytonutrients can be obtained, however, by consuming fruits and vegetables. If alcohol is consumed, cancer survivors should be encouraged to limit its use to no more than one to two drinks per day.
| DIETARY REGIMENS |
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Fasting Therapy
Fasting involves deliberately avoiding food, sometimes for long periods of time. Fasting is believed by its advocates to be an effective way of enabling the body to rid itself of toxins while promoting healing. There is no evidence to support fasting as a healthy practice during cancer therapy or beyond. In fact, fasting can be a very risky practice during the cancer treatment phase, when there is an exceptionally high need for calories and nutrients.
Juice Therapies
Juice therapies promote the use of fresh fruit and vegetable juices as primary sources of nourishment. Advocates say that this practice also stimulates the immune system, reduces blood pressure, and aids in the detoxification of the body.
While the many health benefits of fruits and vegetables are well documented, recommendations specific to juice therapy are not. Juices should not be used as exclusive food sources, but are excellent sources of micronutrients when combined with a balanced diet. Survivors can comply with the ACS recommendation regarding consumption of at least five servings of whole fruits and vegetables daily for cancer prevention by the practice of juicing.
One caveat about juicing should be raised: Commercially prepared unpasteurized juices and ciders may contain pathogenic bacteria, which can be especially dangerous for some cancer survivors.31
Vegetarian Diets
Vegetarian diets include many health-promoting features, as they tend to be low in saturated fats and high in fiber, vitamins, and phytochemicals (e.g., flavonoids, etc.). It is not possible to conclude at this time, however, that a vegetarian diet has any special benefits for the prevention of cancer recurrence. Vegetarian diets differ with respect to specific features, although all avoid consumption of red meat. The greater the restriction of food groups in a particular diet, the more concern there should be about preventing dietary deficiencies. Strict vegetarian diets that avoid all animal products, including milk and eggs, should be supplemented with vitamin B12.99–104
Macrobiotic Diets
Macrobiotic diets are vegetarian in the sense that they minimize consumption of animal products except for a small amount of white fish. Macrobiotic diets are based on whole grains and cereals, vegetables, sea vegetables, beans, fermented soy products, fruits, nuts, seeds, soups made from these ingredients, and teas.99 Individualized diets are based on whether a cancer is classified—according to the Eastern classification system—as being "yin," "yang," or "neutral." Macrobiotic diets can be consistent with a healthy diet, but survivors consuming a macrobiotic diet should take care to consume adequate calories and to obtain sufficient nutrients. While some research supports the health benefits of macrobiotic diets, outcome studies in cancer have been limited and remain controversial. There are no data to support the claim that a macrobiotic diet reduces cancer incidence or recurrence to a greater degree than simply following ACS dietary guidelines.
| DIETARY SUPPLEMENTS |
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The belief that an herbal or botanical supplement is "natural" and therefore can be only beneficial, even in high doses, is clearly incorrect. Many vitamins and herbal compounds are toxic at high levels. The current lack of regulatory oversight of dietary supplements has led to misleading health claims and, in many cases, hazardous doses and contaminants in marketed products. Consumers should be warned about the use of high-dose supplements of any type.
Folic acid and its derivatives should be avoided with methotrexate administration, as this nutritional sup-plement can alter the efficacy of the chemotherapeutic agent.
One of the rationales for taking nutritional supplements stems from observations of lower cancer risk among those who eat diets high in fruits and vegetables, which are rich in essential vitamins and minerals. However, there is no evidence that any nutritional supplements can reproduce the apparent benefits of a diet high in vegetables and fruits.68,105 Pills sold as being equivalent to fruits and vegetables are, in fact, not equivalent, despite the marketing claims of their manufacturers. Although some in vitro and animal studies have suggested possible benefits with high doses of single vitamins and minerals, there is little evidence from human epidemiological or clinical studies to confirm their safety or efficacy. In fact, a nutrient previously thought to be both safe and beneficial (beta carotene) was actually found to increase lung cancer risk in heavy cigarette smokers after it was tested in two large studies.106,107 This suggests that nutritional supplements containing high levels of single nutrients (i.e., greater than the Dietary Reference Intakes and the tolerable upper intake limits) may have unanticipated adverse effects on cancer survivors.
As mentioned, a current area of controversy is the advisability of using nutritional supplements during cancer treatment. Folic acid and its derivatives, for example, should be avoided with methotrexate administration, as this nutritional supplement can alter the efficacy of the chemotherapeutic agent.108,109 For this reason alone, it is always advisable for health care providers to question survivors under their care about any vitamin supplement use during treatment. As previously noted in the section "Phase I: Cancer Treatment," page 155, there is some reason to suspect that high doses of antioxidant supplements might interfere with free radical mediated-cytotoxic mechanisms of radiotherapy and some chemotherapeutic agents.
Despite the lack of firm evidence, it may be reasonable to use nutritional supplements after the active treatment phase for cancer survivors who cannot eat enough to obtain sufficient nutrients. The effects of illness and its treatment, as well as dietary deficiencies, can weaken the body, including the immune system. Although many commercial supplements are promoted to enhance the immune system, some can actually suppress the immune sys-tem. 110 Cancer survivors should be especially cautious of regimens that suggest high supplemental doses of any single nutrient, or drastic eating changes, as a deficiency of any essential vitamin or mineral during cancer treatment and recovery can weaken the immune system.
A reasonable health recommendation to aid recovery after treatment would be for cancer survivors to use a balanced multiple vitamin and mineral supplement (once or twice a day) to correct possible deficiencies. Multivitamin supplements of this type are manufactured by a wide variety of companies, with levels of nutrients usually at approximately the levels recommended for daily consumption [now expressed on labels as the % Daily Value (DV)], formerly known as the Recommended Daily Allowance.
The DV is the average daily dietary intake level that is sufficient to meet the nutrient requirements of nearly all (97% to 98%) individuals in a specific life stage and gender group, and is intended primarily for use as a goal for daily intake by individuals.12–16 The DV is set considerably higher than the estimated average requirement to account for variability in absorption and need. Although nutritional supplementation at doses higher than twice the DV may sometimes be recommended by physicians based on consideration of an individuals diet and disease state, it is generally unwise to initiate such regimens without medical consultation.
One nutritional supplement, beta carotene, has shown some promise in correcting oral leukoplakia, a premalignant lesion of the mouth.111 Nevertheless, overall, beta carotene supplements are more harmful than beneficial.106,107 Early results from uncontrolled trials suggesting that vitamin C and beta carotene were beneficial for cervical cancer were not supported in a properly controlled trial.112 And, there is no good evidence that taking supplements of vitamins A, C, or E at doses above the DV is associated with any clinical benefit.113
Despite the many gaps in scientific knowledge about supplements, many cancer survivors take supplements and are eager to learn more about them. Information provided by manufacturers, retailers, or distributors of supplements is rarely unbiased. Health care providers should be sure to question survivors under their care about whether they are using nutritional and herbal supplement products, especially during chemotherapy or radiation therapy. Survivors should also be counseled against self-prescribing high doses of supplements. It is not wise to assume the safety of high-dose supplements, as there are many uncertainties about their effects and their interactions with other treatments.114–116
| NUTRITIONAL ISSUES IN COMPLEMENTARY AND ALTERNATIVE MEDICINE |
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"Alternative" refers to treatments that are promoted as cancer cures. They are unproven because they have not been scientifically tested, or were tested and found to be ineffective. If used instead of evidence-based treatment, the survivor may suffer, either because helpful treatment is not received or because the alternative treatment is harmful. Personal testimonials are often offered as evidence of the efficacy and safety of these methods, and the treatment is often claimed to be effective in other diseases as well as cancer. Nutritional methods used within complementary and alternative medicine generally encompass vitamin and mineral supplements, herbal and botanical supplements, and dietary regimens.100–104,110,117–138
Cancer survivors may be interested in using complementary or alternative medicine, including nutritional therapies, to enhance the effects of treatment, to protect against treatment-related side effects, or to improve quality of life during treatment and recovery. The use of such therapies has greatly increased in recent years.117 Survivors may believe that such therapies are "natural" and therefore also harmless, an assumption that may not be correct. It is important for health care providers and survivors to discuss the use of complementary or alternative therapies so that survivors are fully informed regarding both possible benefits and risks.
In the absence of firm scientific evidence from controlled clinical trials, survivors need to make decisions about complementary and alternative therapies based on uncertain claims. Data that do not meet the usual standards of scientific proof include anecdotal reports of efficacy, uncontrolled trials, traditional use suggesting a lack of harm, and the plausibility of biological mechanisms of action.
Only a few of these traditional supplements have been studied scientifically to evaluate their effects on cancer.
Some herbal and botanical supplements have a long history of use in other cultures, suggesting safety when used according to traditional methods. Only a few of these traditional supplements have been studied scientifically to evaluate their effects on cancer. Little is known about the use of commonly available herbal and botanical supplements by cancer survivors. This lack of knowledge is a strong argument for more clinical research and physician education in this area. Reliable information about the functions of supplements and their therapeutic doses is difficult to find.
For a few supplements, clinical and preclinical research provides evidence of benefit in some situations. However, for most, current information must be considered preliminary, as there have been so few controlled clinical trials. Even in the best cases, currently available research findings can only be regarded as preliminary. Survivors should discuss their choices with their practitioners so that regimens can be tailored and monitored to reduce the possibility of adverse effects such as drug/nutrient interactions or toxicities.
The following nutritional therapies are highlighted because of their popularity among cancer survivors. Several other therapies are discussed in the longer version of this document that is available online (www.cancer.org). For information on additional complementary and alternative therapies, refer to the American Cancer Societys Guide to Complementary and Alternative Cancer Methods (Atlanta, GA: American Cancer Society, 2000) or call the American Cancer Society (1-800-ACS-2345).
Flaxseed and Fish Oils
Flaxseed and fish oils both contain omega-3 fatty acids, substances associated with reduction of heart disease risk. Some preclinical studies suggest that omega-3 fatty acids reduce tumor growth and metastasis, but others show an increase in such effects. At the present time, therefore, evidence is insufficient to recommend dietary supplementation with either flaxseed oil or fish oils to reduce the risk of cancer recurrence or to improve prognosis.139–141
Ginger
Although ginger does have antinausea properties and is useful in the management of motion sickness, it may not be an effective antiemetic agent during chemotherapy. This is because its activity is due to a local effect in the stomach rather than on the central nervous system. Nausea induced by chemotherapy often requires specific prescription medications that can block and prevent the stimulation of the emetic response at the level of the central nervous system. The taste and aroma of ginger and ginger-containing foods and beverages may be calming for some individuals, but large doses of ginger in pill form have been shown to cause depression and cardiac arrhythmias.142–144
Soy Foods
While there is tremendous public and scientific enthusiasm for the use of soy foods in the prevention of recurrences of breast and prostate cancers, scientific support for such recommendations is remarkably inconsistent. Interest in soy foods stems from the observation that they are used commonly in Asia, where the rates of breast and prostate cancer are lower than in the US. Soy contains high levels of plant isoflavones (genistein and diadzein), which exert a variety of anticancer activities in laboratory studies. Some of these isoflavone compounds can act like "estrogens" or "anti-estrogens" in the body. Perhaps because soy has the potential for producing both types of effects, studies on soy and breast cancer have produced conflicting results, with some showing genistein to inhibit the growth of breast cells and others showing stimulatory effects.
Several trials are examining the effects of soy components on cancer risk. Until these trials are concluded, there is insufficient information to make a recommendation about use of soy foods for cancer survivors. These products may have beneficial effects for some, and adverse effects for others.145–155
Teas
Some evidence suggests that tea consumption, including both green and black teas, could reduce the risk of cancer. Epidemiologic evidence suggests that cancer risk might be lower among those who drink teas, especially green teas, which contain high levels of polyphenols, a family of antioxidant phytochemicals. Whether this is a specific effect of teas per se or other dietary or behavioral factors common among tea drinkers is not yet established. Although tea polyphenols can affect the growth of cancer cells in vitro, very little research has been done on the specific effects of tea consumption among cancer survivors. Preliminary laboratory studies looking at green tea intake and breast cancer growth have been performed, and studies on prostate cancer growth are planned or in progress.17–165
Except for its mild stimulant activity, which may cause problems among people prone to cardiac arrythmias, insomnia, or anxiety, moderate amounts of green or black teas can be considered safe. These teas, however, should not be confused with teas made from plants not ordinarily used for foods or beverages. The latter are often promoted as alternative therapies, and some are associated with significant toxicities.
| NUTRITIONAL ISSUES FOR COMMON CANCER SITES |
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Weight Maintenance and Dietary Fat
Obesity has been shown to adversely affect prognosis, so breast cancer survivors should be encouraged to achieve and maintain a healthy weight that is appropriate for their height. Moderate physical activity during and after treatment will help survivors maintain lean muscle mass while avoiding excess body fat.4 Even if ideal weight reduction is not achieved, it is likely that any amount of weight loss with the goal of normalizing weight levels is beneficial and therefore should be encouraged.37–43 However, weight loss should not be attempted during active treatment, but should be initiated during the recovery phase. Weight loss of one to two pounds a week is recommended, whereas more rapid weight loss requires expert nutritional supervision.
| ACS Workgroup Grading System for Evaluating Benefit Versus Harm To summarize the strength of the scientific evidence, the ACS Workgroup used a method of summarizing the evidence similar to those used by other expert panels. For example, the US Preventive Services Task Force judged the scientific evidence related to clinical preventive services using a system that considered both the source and strength of the evidence and categorized them as follows: From at least one controlled clinical trial, from good uncontrolled trials, from multiple good observation studies, expert opinion, and case reports. They then characterized those recommendations on a five-point grading scheme as to the strength of the recommendation: Good for recommending, fair for recommending, insufficient to recommend for or against, fair for not recommending, or good for not recommending. The AICR-World Cancer Research Fund project summarized the nature of the scientific evidence for nutritional factors in cancer prevention as being either Convincing, Probable, Possible, or Insufficient. The ACS committee employed a method of summarizing the evidence that was similar to those used by both groups. For each issue, the committee judged the likelihood of benefit to cancer survivors as follows:
Table 3
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With nutritional supervision, a low-fat diet, even as low as 20% of calories from fat, can be started during therapy or can be initiated following treatment, in the recovery period. Breast cancer survivors should obtain the majority of their added fat from monounsaturated fats sources such as olive or canola oil, avocado, and nuts. In addition, they should limit their intake of saturated fats from sources such as red meat, poultry, and fat-containing dairy products.
Insufficient scientific evidence exists to make specific recommendations with regard to the effects of omega-3 fatty acids or fish oil supplements on breast cancer.139–140 The use of concentrated omega-3 fatty acid supplements and flaxseed oil can not be recommended at this time. Nevertheless, although such supplements are not advisable, food sources that contain these nutrients, such as fish (salmon, trout, sardines), are recommended. Several studies in this area are underway, but at this time, breast cancer survivors should be encouraged to select foods that are good sources of omega-3 fatty acids, such as fish and walnuts, while adhering to a low-fat diet.
Soy
Soy, soy-containing foods, and soy components such as isoflavones, exert both estrogenic and antiestrogenic effects.145–154 Soy may also have other anticancer effects not related to phytoestrogens.156 There is conflicting scientific information regarding the actual health benefit of soy at this time. Although the antiestrogenic effects of soy may mimic the beneficial effects of pharmacological antiestrogens such as tamoxifen, soy can also be proestrogenic, demonstrating adverse effects on markers of cancer risk in breast tissues.148 Therefore, it would be most prudent for breast cancer survivors to use only moderate amounts of soy foods as part of a healthy plant-based diet, avoiding very high levels of soy. Moreover, breast cancer survivors should not intentionally augment their diets with more concentrated sources of soy, such as soy-containing pills or powders, or supplements containing isolated or concentrated isoflavones.
Alcohol
Research has shown that consumption of alcohol is associated with an increased risk of breast cancer.37 The adverse effects of alcohol on breast cancer risk may be due to the effects of alcohol on estrogen levels in women. As the effects of alcohol on breast cancer survival are unknown at this time, it would be prudent to avoid high levels of alcohol (more than one to two drinks per day). For women with estrogen-responsive breast cancers, however, total avoidance of alcohol may be the best choice.
Fruits and Vegetables
Fruits and vegetables contain many phytochemicals that may help to prevent cancer or improve cancer prognosis. All cancer survivors, including breast cancer survivors, should be encouraged to consume at least five servings of fruits and vegetables per day. Although the correlation between dietary fiber and breast cancer recurrence is not clear, high fiber intake may reduce estrogen levels. A diet high in whole grains, legumes, vegetables, and fruit, is a good choice for breast cancer survivors.2
Physical Activity
There is growing evidence that regular physical activity may be beneficial for breast cancer prevention, especially in premenopausal women.71–77 Additional benefits of regular physical activity include prevention and management of heart disease and osteoporosis, as well as improved quality of life. Regular physical activity is essential for weight management.
Prostate Cancer
Although most men develop latent prostate cancer with advancing age, such prostate tumors remain small, are confined within the prostate gland, and do not cause symptoms. The incidence of small, localized prostate cancers is roughly similar in young men around the world, but evolution of those cancers to more aggressive, symptomatic disease occurs as men age at a higher rate in western nations than among men living in Asia. Prostate cancer is especially aggressive among African-Americans, although the reasons for this are unknown.
Dietary Fat
Most research on diet and prostate cancer has focused on prostate cancer incidence. Dietary factors that are associated with reduced prostate cancer incidence might also reduce the rate of prostate cancer growth after diagnosis, thus preventing or slowing progression of early-stage prostate cancer. High intake of foods from animal sources, especially foods high in saturated fat, have been associated with increased prostate cancer risk.45 High-fat diets can also increase testosterone levels, which may account for their apparent stimulatory effect on prostate cancer growth.166,167
Consumption of a diet high in saturated fats has also been linked to heart disease. Older men with early-stage prostate cancer are actually at higher risk of death from heart disease than from prostate cancer, so it is especially wise for prostate cancer survivors to follow a heart-healthy diet that is low in saturated fat, high in fruits and vegetables, and accompanied by regular physical activity.
Lycopene
Lycopene, the red-orange carotenoid anti-oxidant found at high levels in vegetables such as tomatoes and tomato-based foods, is commonly recommended for prostate cancer survivors. This recommendation comes from epidemiologic research suggesting that diets high in tomato products might be associated with lower prostate cancer incidence.168–170 Although lycopene may indeed be beneficial for the prostate, this hypothesis is not documented and requires further study. Even if lycopene in a healthy diet is associated with lower risk for prostate cancer, it does not follow that high doses would be either more effective than the lycopene in the diet or that high doses of a supplement would be safe.
Many studies have shown dietary levels of beta carotene to be associated with lower risk for lung cancer, but two trials using high-dose supplements of beta carotene have now shown that high dose supplements actually increase (not decrease) the rate of occurrence of lung cancer.106,107 High doses of single nutrients taken as supplements appear to be capable of interfering with normal nutritional processes to increase cancer risk.
Selenium
Selenium is a trace mineral that has been thought to reduce prostate cancer risk. In a randomized controlled trial for skin cancer prevention, selenium supplementation with 200 mcg per day had no effect on skin cancer, but it did reduce prostate cancer incidence.171 Whether this was a chance finding or a true beneficial effect is unknown. Another study has also found that men with the highest level of selenium (measured by toenail selenium content) had a reduced risk of advanced prostate cancer compared with the group with the lowest selenium levels.172
At this point, selenium supplementation cannot be recommended with confidence, but if a selenium supplement is used, it would be prudent to limit the dose to 200 mcg per day. The best source of selenium in supplement form is in a selenium-enriched brewers yeast rather than inorganic selenium (e.g., selenite), because the latter is more likely to cause hepatic and brain toxicities at high doses.
Vitamin E
In the Alpha Tocopherol and Beta Carotene (ATBC) Study, which was designed principally to test the effects of beta carotene and/or vitamin E (alpha tocopherol) supplementation on lung cancer risk, the men who were assigned to take vitamin E (50 mg per day) had a lower incidence of prostate cancer than did the men taking a placebo.173
Increased consumption of foods rich in vitamin E or supplements may decrease the rate of conversion from latent to aggressive forms of prostate cancer, but confirmatory studies are needed. Importantly, though, total mortality was not lower among those taking vitamin E—actually it was a bit higher due to episodes of bleeding and hemorrhagic strokes.
Whether vitamin E may decrease the rate of conversion from latent to aggressive prostate cancer is still unknown, and the risk/benefit ratio of taking supplementary vitamin E for cancer prevention is uncertain.174 It would be prudent to limit the intake of vitamin E to 400 to 800 mg per day if supplements are used.
Total mortality was not lower among those taking vitamin E—actually it was a bit higher due to episodes of bleeding and hemorrhagic strokes.
Examples of foods rich in vitamin E include wheat germ, green leafy vegetables, seeds, nuts, and vegetable oils. A large prostate cancer prevention trial (SELECT) is now underway to test the ability of vitamin E (400 mg per day) and/or selenium (200 mcg per day) to reduce prostate cancer risk.175
Soy
As soy protein products contain active phytoestrogens (such as isoflavones), increased consumption of soy foods, such as tofu, soy milk, and other soy-containing foods, is commonly recommended for prostate cancer survivors. There have been no good studies of the effects of soy or other phytoestrogens, however, on the growth of prostate cancer after diagnosis of advanced disease, but trials are currently underway.
Calcium
Some epidemiological studies have shown that men who have high levels of calcium in their diets might be at increased risk for prostate cancer incidence.176 Calcium, especially when taken as supplements, has the ability to temporarily suppress circulating levels of vitamin D in the blood. Because vitamin D is thought to be important in decreasing the growth of prostate cells, it is hypothesized that high levels of calcium in the diet, including from calcium supplementation, might increase prostate cancer risk. The possible effects of calcium after prostate cancer treatment, however, are unknown at this time.
During treatment of prostate cancer, it is important to eat a healthy diet that meets the additional nutritional needs caused by surgery, chemotherapy, or radiation therapy. It is also important that prostate cancer survivors tell health care providers which vitamin, mineral, or herbal supplements they might be taking, as some may interfere with treatment.
Lung Cancer
Diets low in fruits and vegetables have been shown to increase lung cancer risk, even after accounting for the fact that smokers tend to have poorer diets than nonsmokers.177 This observation led to the idea that perhaps the antioxidant nutrient beta carotene, found in fruits and vegetables, might reduce lung cancer risk if taken in high doses. However, two large randomized controlled trials showed increased risk with high-dose beta carotene supplementation.106,107 The possible impact (either beneficial or harmful) of nutritional supplements after the diagnosis of lung cancer has not been studied.
Selenium
The only nutritional supplement found to have a beneficial effect on lung cancer incidence has been selenium. In a study intended to assess the impact of selenium (200 mcg per day) on skin cancer, it was observed that fewer lung cancer cases (and deaths) occurred in the group given selenium.171 This observation is now being formally tested in a trial of selenium after the diagnosis of early-stage lung cancer to determine whether selenium might have benefits with respect to lung cancer prognosis and/or the development of second primary cancers.177 In an earlier study, despite experimental animal evidence of a possible benefit of vitamin A on the course of lung cancer, vitamin A was found not to be beneficial as an adjunct to lung cancer treatment.178
Nutrition During and After Lung Cancer Treatment
Lung cancer treatment (i.e., surgery, radiation, chemotherapy) is often aggressive and causes side effects such as esophagitis resulting in dysphagia, fatigue, nausea, and vomiting that can impinge on nutritional well-being. Many survivors exihibit low blood nutrient levels, even before diagnosis, due to inadequate diets and/or to the adverse effects of smoking on micronutrients. It is important, therefore, to make special efforts to regain nutritional health during treatment and recovery. Clinical trials testing the effects of dietary and physical activity/exercise interventions specifically with lung cancer patients are needed. During treatment and the immediate recovery period, lung cancer survivors may benefit from eating foods that provide concentrated calories and are easy to swallow. Small, frequent meals may be easier to manage than three large meals per day.
Because intake of fruits and vegetables is strongly associated with prevention of lung cancer, it is reasonable to expect that such benefits might carry over into treatment and recovery. Survivors may need extra help with dietary intake, and may benefit from appetite stimulants, and from juicing fruits and vegetables.
Nutritional supplements may be especially helpful as dietary adjuncts. Homemade drinks and shakes and commercially produced formulas (e.g., Boost,® Ensure,® Resource,® or NuBasics®) can be used to augment healthy diets when needed to compensate for increased nutritional needs.
Survivors frequently exhibit nutrient deficiencies and cannot eat enough to adequately meet micronutrient needs. In such situations, a multivitamin-multimineral supplement is advisable, either in pill or liquid form. High doses of vitamins and minerals, however, should be used cautiously.
Head and Neck Cancers
The comprehensive care of survivors with upper aerodigestive-tract cancer includes ap-propriate nutritional assessment/support and physical activity/therapy to improve overall health before, during, and after treatment. Survivors receiving adequate nutrition maintain body weight and complete treatment with fewer complications.179
After treatment for cancers of the head and neck, poor nutrient intake can result from difficulties in biting, chewing, and swallowing, as well as from xerostomia as a complication of radiation therapy. Inadequate protein and calorie intake can result. During and following treatment, the texture, temperature, consistency, nutrient content, and frequency of oral feedings may need to be changed. Since those who wear dentures may be unable to wear them during and following treatment and may need new dentures to improve oral function, liquid, pureed, or juiced foods may be better tolerated during treatment and recovery. Health care providers may offer alternate forms of feeding if eating and drinking by mouth cannot support nutritional needs.180–186
Individuals with oral leukoplakia, a pre-malignant lesion for oral cancer, benefit from beta carotene supplementation,111 but the risks of beta carotene in higher doses than the Daily Recommended Intakes and tolerable upper intake limits in supplement form seem to outweigh its possible benefits.106,107 Therefore, survivors are encouraged to eat fruits and vegetables that are orange and deep green in color, as they are good sources of naturally occurring beta carotene.
Difficulty swallowing is frequently a presenting symptom of esophageal cancer. Individuals first struggle with solid foods, then progress to difficulty eating soft foods and eventually liquids. As an adjunct to palliative surgical and medical interventions, sitting upright, eating slowly, chewing thoroughly, and consuming small, frequent meals can be helpful.
Another common problem in survivors with esophageal cancer is reflux while eating or just afterward. It is believed that the mechanisms responsible for these symptoms of gas, heartburn, and regurgitation are the direct ir-ritation by food and a weakening of the anti-reflux barrier by reduction of esophageal sphincter pressure.182 Using a high-protein, low-fat, high-carbohydrate regimen helps decrease lower esophageal sphincter pressure, whereas chocolate, fat, alcohol, coffee, and compounds containing carminatives (e.g., oil of spearmint, peppermint, garlic, and onion) may increase lower esophageal sphincter pressure, and should be avoided.182 Acidic foods such as tomato-based products and orange juice may cause irritation.
Using a high-protein, low fat, high-carbohydrate regimen helps decrease lower esophageal sphincter pressure.
Gastric Cancer
Nutritional management for individuals who have gastric cancer is based on determining what portion of the stomach is involved or has been surgically removed or altered. If the pyloric sphincter has been affected, then refluxing and/or rapid transit of foods through the stomach may occur. Rapid transit will lead to cramps, distention, and diarrhea. Eating slowly, in small, frequent feedings, with most liquids sipped slowly between meals, can assist in processing food. Foods high in concentrated sweets, such as sugar, honey, molasses, jams, icings, frostings, ices, ice cream, and soft drinks should be avoided.
Fullness, or early satiety may represent a problem as survivors try to meet nutritional needs. Some survivors may experience fat intolerance, so lowering the amount of fat in the diet can decrease symptoms. Milk intolerance also develops in some post-surgical gastric cancer survivors. Use of lactose-free dairy products or commercial beverages can augment food selections. Developing an individualized nutritional care plan that includes a strategy for meeting calorie needs, specific recommendations, and food choices is advised for survivors of gastric cancer.
Colorectal cancer incidence seems to be increased by diets high in saturated fats and low in fruits and vegetables, as well as by sedentary lifestyles and obesity.
Colorectal Cancer
Colorectal cancer incidence seems to be increased by diets high in saturated fats and low in fruits and vegetables, as well as by sedentary lifestyles and obesity.44 After a diagnosis of colorectal cancer, the most important determinants of survival seem to be adherence to the full treatment regimen (especially if chemotherapy is recommended) and colonoscopic surveillance to look for new lesions.
Selenium
Selenium supplementation was associated with reduced risk of colorectal cancer diagnosis in a trial designed to affect skin cancer incidence,171 but whether selenium might be beneficial after colorectal cancer diagnosis is un-certain. If selenium is taken, it should be as a brewers yeast preparation in doses no higher than 200 mcg per day.
High Dietary Fiber
Although high-fiber diets have been recommended to reduce colorectal cancer risk, there is more evidence of a benefit with respect to general bowel function (e.g., preventing constipation) than for colorectal cancer risk reduction. Colorectal cancer survivors can have residual problems with bowel function (both diarrhea and constipation) after treatment. Survivors should be advised to maintain a reasonable weight, eat a well-balanced diet, and participate in regular physical activity after treatment. Colorectal cancer survivors with chronic bowel problems should be referred to a qualified nutritionist to modify diet and activity.
As colorectal cancers arise from adenomatous polyps, the prevention of polyp growth has been a focus of considerable clinical research. To date, trials have failed to show benefits over a three-year period from taking antioxidant vitamins, fiber supplements, or modest dietary changes with respect to preventing new polyp growth.105,187–189 There was a modest benefit from calcium supplements, however, in terms of reducing polyp growth. Trials testing the effects of aspirin and folic acid are underway.105,190
| CANCER PREVENTION FOR FAMILY MEMBERS |
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People concerned about the possibility of having inherited an increased risk of developing cancer should speak with a genetic counselor or physician with training and experience in cancer genetics. Based on the family history and, in some cases, genetic testing, an intensified program of early detection, prophylactic surgery, and chemoprevention may be considered. In addition, family members who wish to reduce their risk of cancer should follow the ACS Guidelines for Nutrition and Physical Activity for Cancer Prevention. Following these guidelines may also reduce the risk of heart disease, diabetes, and obesity.2–6
| PROMOTING INFORMED DECISION-MAKING BY SURVIVORS |
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It is important to recognize that the search for information can be confusing, even when credible sources of information are found. At times, even reputable sources of information provide conflicting information. Such differences of opinion arise when there is no solid evidence regarding the best way to treat a particular condition. In these cases, survivors should consult with a number of different health care providers to decide their best course of treatment. They should especially seek out information to help formulate decisions on the use of supplements or complementary and alternative therapies, then communicate any such decisions with members of the health care team. This is important so that the team can be aware of any potential interactions that may interfere with treatment.
Survivor-Provider Communication
Many cancer survivors are reluctant or unable to describe their feelings and concerns about their experience with family members, friends, and their health care providers. This difficulty often stems from not being able to articulate such a complex experience with words.
Health care providers are also confronted with information that can be confusing. Because there are so many unanswered questions and because the science of nutrition in cancer survivors is so limited, health care providers can sometimes appear to be impatient with questions. This can cause cancer survivors either to avoid addressing their nutritional concerns with their providers, or to seek answers only from sources of questionable credibility.
Health care providers should encourage questions and should provide referrals to other professionals, such as physicians, registered nurses, registered dietitians, social workers, physical therapists, or researchers, when appropriate.
To enhance candid communication, survivors should be encouraged to:
Making Informed Choices
Informed choice ensures that survivors are comfortable with the decisions that have been made, and provides the rationale for understanding and support from others regarding these decisions. Armed with good information, survivors can fully assess whether or not any particular choice will assist in meeting their objectives. The most important feature of making informed choices is to periodically reassess and update both the information and ones personal objectives, balancing them realistically against changing health needs through the phases of cancer survivorship.
| Footnotes |
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This article is also available online at www.cancer.org.
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