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Dr. Armitage is Professor, Department of Internal Medicine, Joe Shapiro Distinguished Chair of Oncology, University of Nebraska Medicine Center, Omaha, NE.
| ABSTRACT |
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| INTRODUCTION |
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Assigning a stage to a newly diagnosed patient with non-Hodgkin Lymphoma is no less important than for other cancers. However, the development of a staging system for non-Hodgkin Lymphoma has been a difficult and complicated process. This is, at least in part, due to the heterogeneous nature of illnesses encompassed in the term "non-Hodgkin Lymphoma." Lymphoid malignancies are generally classified as leukemia if they involve primarily the blood and bone marrow and as lymphoma if they present as tumors in lymph nodes or other organs. However, almost all lymphoid malignancies can have either presentation and some are almost equally likely to present as a leukemia or lymphoma. In addition, immune system malignancies represent a spectrum from some of the most indolent malignancies (eg, some mucosa-associated lymphoid tissue [MALT] lymphomas) to the most rapidly progressive human cancers (eg, Burkitt lymphoma).
The first system widely utilized for staging non-Hodgkin Lymphomas was actually developed for staging Hodgkin disease and is referred to as the Ann Arbor Staging System.1 Although primarily an anatomic staging system, the Ann Arbor stages are modified by the presence or absence of systemic symptoms. It was adjusted over the years for the use in staging Hodgkin disease,2 but still represents a backbone of the staging system recommended today for non-Hodgkin Lymphomas. However, recognition that the Ann Arbor system does not subdivide some types of non-Hodgkin Lymphomas in a clinically useful way, and the recognition that other factors are important in predicting treatment outcome, led to the development of the International Prognostic Index in 1993.3 The recommendation for the evaluation of a new patient diagnosed with non-Hodgkin Lymphoma currently involves application of both these systems.
The current recommendations for staging non-Hodgkin Lymphoma adopted by the American Joint Commission on Cancer are published in the Cancer Staging Manual, sixth edition.4 These have been developed by a committee of experts and are reviewed on a regular basis. The membership of the committee on staging lymphoid neoplasms can be found in Table 1.
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| CLASSIFICATION OF NON-HODGKIN LYMPHOMA |
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The use of multiple systems of classification throughout the world posed serious difficulties for therapeutic research. It was difficult or impossible to compare the results of therapeutic trials when different systems of classification were utilized. To solve this problem, the Working Formulation was developed as a compromise system.10 The Working Formulation adopted some aspects of the Rappaport Classification, the Lukes-Collins Classification, and Kiel Classification and was the primary system used in publications in much of the 1980s and 1990s. However, it never became as popular in Europe as in North America. The 1980s and 1990s also saw striking advances in our understanding of biology of the immune system and recognition that some lymphomas didnt fit easily into the existing categories. The study of lymphomas carrying the t(11;14) and overexpressing the associated Bcl-1 protein led to the acceptance of mantle cell lymphoma as a specific diagnosis.11 The discovery of CD30 (formerly Ki-1) and the recognition that some malignancies marked by CD30 had a t(2;5) and overexpression of the ALK protein led to the acceptance of anaplastic large T/null cell lymphoma as a distinct clinical entity.12–16 Also, the description of small B-cell lymphomas occurring in association with epithelial tissue, sometimes developing in association with specific infections, led to acceptance of the concept of MALT lymphomas.17,18 Of course, the prototype MALT lymphoma occurs in the stomach and is usually associated with infection by Helicobacter pylori. None of these new lymphomas fit easily into a preexisting category in the widely used classification systems and, in fact, generally were found in several different categories.
In the 1990s, a group of hematopathologists proposed a new system to take into account advances in understanding the biology of the immune system and the recognition of these newly accepted subtypes of non-Hodgkin Lymphoma, termed the Revised European American Lymphoma (REAL) classification.19 Diagnoses in the REAL classification were based on morphology, immunology, and clinical characteristics. Study of the REAL classification showed that it was clinically relevant and more reproducible than previous systems.20 The concepts embodied in the REAL classification were used to develop the World Health Organization (WHO) classification of lymphoma that is currently the gold standard throughout the world.21
The WHO classification is presented in Table 2. It subdivides tumors into those of B-cell versus T/NK-cell origin and those with an immature or blastic appearance versus those developing from more mature stages of lymphoid development. The latter tumors, in the case of T-cell lymphomas, were referred to as "peripheral" T-cell lymphomas. Today, the first step in evaluation of any patient with non-Hodgkin Lymphoma should be classification of their tumor in the World Health Organization classification. This should include the performance of immunophenotyping and might require cytogenetics, fluorescent in situ hybridization (FISH), antigen receptor gene rearrangement studies, and other investigations. If at all possible, this should be done by an experienced hematopathologist working with an excisional biopsy of an affected lymph node or extra lymphatic tumor. Large cutting needle biopsies are an alternative in selected cases where excisional biopsy is difficult or dangerous. Fine-needle aspirates are not appropriate and should not be the basis for primary diagnosis of non-Hodgkin Lymphoma and the subsequent choice of therapy.22
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| ANN ARBOR STAGING |
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The Ann Arbor staging system divides patients into four stages based on localized disease, multiple sites of disease on one or the other side of the diaphragm, lymphatic disease on both sides of the diaphragm, and disseminated extranodal disease (Table 3). Localized extranodal sites of involvement are recognized by a subscript E.
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The definition of these stages as found in the Cancer Staging Manual is as follows: Stage I: Involvement of a single lymph node region (I), or localized involvement of a single extralymphatic organ or site in the absence of any lymph node involvement (IE) (rare in Hodgkin disease). Stage II: Involvement of two or more lymph node regions on the same side of the diaphragm (II), or localized involvement of a single extralymphatic organ or site in association with regional lymph node involvement with or without involvement of other lymph node regions on the same side of the diaphragm (IIE). The number of regions involved may be indicated by a subscript, for example, II3. Stage III: Involvement of lymph node regions on both sides of the diaphragm (III), which also may be accompanied by extralymphatic extension in association with adjacent lymph node involvement (IIIE) or by involvement of the spleen (IIIS) or both (IIIE,S). Stage IV: Diffuse or disseminated involvement of one or more extralymphatic organs, with or without associated lymph node involvement; or isolated extralymphatic organ involvement in the absence of adjacent regional lymph node involvement, but in conjunction with disease in distant site(s). Any involvement of the liver or bone marrow, or nodular involvement of the lung(s) is always Stage IV. The location of Stage IV disease is identified further by specifying site according to the notations listed for Stage III.
The distinction between Stage I and Stage II involvement is based not on individual lymph nodes but on what are termed as "lymph node regions." Lymph node regions were defined at the Rye Symposium in 1965 and have been accepted by convention since that time. The lymph node regions include right cervical (including cervical, supraclavicular, occipital, and preauricular lymph nodes), left cervical, right axillary, left axillary, right infraclavicular, left infraclavicular, mediastinal, hilar, periaortic, messentary, right pelvic, left pelvic, right inguinal femoral, and left inguinal femoral. Multiple lymph nodes palpable in one of these regions would be Stage I, and involvement of two of these regions but on one side of the diaphragm would represent Stage II. Unlike Hodgkin disease, it is not uncommon for non-Hodgkin Lymphoma to involve other lymph node sites not included in the core sites from the original Ann Arbor classification. These might include epitraoclear, popliteal, internal mammary, occipital, submental, perauricular, and other small lymph node areas. Each of these could also be considered a separate lymph node site and used in the distinction between Stage I and Stage II.
The designation of Stage IV disease implies disseminated disease involving extranodal sites. However, by convention, involvement of the bone marrow, liver, pleura, and cerebrospinal fluid are always considered Stage IV even if the disease is isolated to that organ. Lymphatic involvement in a draining area from a primary extranodal lymphoma should be designated as IIE (eg, a thyroid lymphoma with cervical lymph node involvement). Lymphoma extending beyond the lymph node capsule involving adjacent organs should also receive the E suffix and not be called Stage IV (eg, lymphoma in mediastinal lymph nodes growing directly into adjacent lung). It is true that unusual cases might lead to debate about the appropriate assignment of Stage IIE or Stage IV, and sometimes even experts can disagree about which would be most appropriate.
Anatomic staging in non-Hodgkin Lymphoma can be done using history, physical examination, laboratory studies, and images, in addition to definitive proof of involvement of a particular site from biopsy. As a practical point, most patients are assigned their stage based on the results of noninvasive studies rather than having biopsies to document each apparent site of involvement.
Appropriate clinical staging includes: a careful recording of history and physical examination; appropriate images of the chest, abdomen, and pelvis; blood chemistry measurements; complete blood count; and bone marrow biopsy. The basic staging and investigation for a patient with non-Hodgkin Lymphoma includes all these studies with images usually obtained using computed tomography (CT) scans. In patients unable to safely undergo a CT scan, magnetic resonance imaging studies are often substituted. Recent advances in functional imaging using positron emission tomography scans have expanded the possibilities for imaging in non-Hodgkin Lymphoma. However, clear definitions of what constitutes a site of involvement and whether or not positron emission tomography scans can substitute for CT scans are a point for debate and investigation. Patients at high risk for central nervous system involvement should have a lumbar puncture and cerebrospinal fluid cytology performed. Bone marrow biopsy is a standard part of the clinical investigation. However, what is an appropriate bone marrow biopsy has been a point of disagreement, with some experts saying that bilateral biopsies are necessary. The most important part of a bone marrow biopsy is obtaining an adequate core for histological evaluation (ie, at least 15 to 20 mm). Whether this is done with one or multiple punctures probably does not matter. Biopsy of other sites (ie, beyond the initial excisional biopsy on which the diagnosis was based) would normally only be done if the results might modify therapy.
In the past there has been debate on how large a lymph node needed to be for it to be considered abnormal. By convention, lymph nodes greater than 1.5 cm in maximum diameter are now considered abnormal and assumed to be involved by disease. Documenting splenic involvement lymphoma can be problematic but is usually done by identifying palpably enlarged spleens or focal defects seen on imaging studies. Liver involvement is usually demonstrated by multiple defects on imaging studies consistent with involvement by neoplasm or by liver biopsy. The presence of a palpable liver or abnormal liver chemistries should not be used alone to assume involvement of the liver by lymphoma. Lung involvement is usually documented by presence of characteristic imaging abnormalities. On occasion, lung biopsy may be necessary to clarify equivocal cases. Clinical involvement of the brain can be documented by characteristic imaging abnormalities in a patient with lymphoma known to metastasize to the brain. However, this is an unusual situation. More commonly, primary brain lymphomas require biopsy to document their presence.
Although more useful in Hodgkin disease, the Ann Arbor Staging system also designates patients as either being suffix A or B. Designation as A indicates the absence of unexplained fever with temperature greater than 38°C, drenching night sweats requiring the change of bedclothes, and unexplained weight loss of more than 10% in the 6 months before diagnosis.
| INTERNATIONAL PROGNOSTIC INDEX |
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Results of the International Prognostic Index study showed that five factors were roughly equal in power in predicting treatment outcome (Table 4). These included age greater or less than 60 years, Ann Arbor Stage I and II versus Stage III or IV, none or one versus two or more sites of extranodal involvement by lymphoma, an Eastern Cooperative Oncology Group performance status (Table 5) of Grade 0 or 1 versus Grade 2 or greater, and a normal versus elevated lactate dehydrogenase (LDH). The number of adverse prognostic factors (ie, age > 60 years, advanced stage, two or more extranodal sites, poor performance status, or elevated LDH) could be simply summed because each had approximately the same power in predicting treatment outcome. Thus, a score of 0 to 5 was possible. The original publication suggested the patients be lumped into groups with a low risk (ie, score of 0 or 1), low intermediate risk (score of 2), a high intermediate group (score of 3), and a high risk (score of 4 or 5). In the original study and in previous experience, there is a highly significant impact on chances to achieve a remission, remain in remission, and overall survival based on the International Prognostic Index score. For example, patients in the low-risk group in the original publication had an 87% complete remission rate and an overall survival of 73% at 5 years versus a 44% complete remission rate and 26% survival at 5 years in the high-risk group (Table 6).3
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Particularly important was documentation that the International Prognostic Index score was able to subdivide patients in Ann Arbor Stage II, III, and IV (Figure 1). The dramatic difference in treatment outcome for patients with the same Ann Arbor Stage found by utilizing the International Prognostic Index undoubtedly explains wide discrepancies in the results of some previous clinical trials. For example, in Phase II trials, several chemotherapy regimens seemed to be superior to cyclophosphamide, doxorubicin, vincristine, and prednisone in the treatment of aggressive lymphoma24–26 but yielded the same outcome in a head-to-head Phase III trial.27 In retrospect, the earlier studies almost certainly treated patients with a better prognosis, although the stages were similar.
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The International Prognostic Index is presented in Table 4. This should be calculated on every new patient with non-Hodgkin Lymphoma and will have an important impact on the treatment decision.
| THE FUTURE |
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None of the systems currently in use for evaluation of adult patients with non-Hodgkin Lymphoma account for the presence of a bulky mass. This probably relates the lack of uniform data collection about the maximum tumor diameter in previous studies. However, the presence of a very large mass is a predictor of poor treatment outcome, and clinicians often take very bulky sites of disease into account by adding radiotherapy to that site.
The primary site of origin of a non-Hodgkin Lymphoma almost certainly affects the biological characteristics of the malignancy. There is no reason to believe that diffuse large B-cell lymphoma originating in different sites of the body would have the same behavior any more than we would think that all squamous cell carcinomas, regardless of origin, would have the same behavior. It is possible that different types of evaluations would be appropriate for tumors originating in different parts of the body.
The most important factor likely to change the way we evaluate patients with lymphoma is the rapidly expanding knowledge about gene expression patterns and protein expression.29,30 It is possible to imagine a time when the only evaluation of a new patient with lymphoma that would be required would be identification of the expression of certain key proteins. If drugs that specifically targeted these proteins were available, and they could cure most or all patients, other evaluation could be superfluous. Although certainly a goal for the future, it is not impossible that we could reach this point.
Whatever the future holds, at the present time an accurate staging evaluation is key to the management of a patient with newly diagnosed non-Hodgkin Lymphoma. Careful application of the systems described in this paper will lead to the best possible treatment outcome.
| Footnotes |
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| REFERENCES |
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