CA: A Cancer Journal for Clinicians, Vol 22, 40-54, Copyright
© 1972 by American Cancer Society
The Pathology of Tumors, Part Five
Functioning Tumors Spread of Cancer The Radiotherapist and the Pathologist
Lauren V. Ackerman M.D.1 and
Juan Rosai M.D.2
1 Professor of Surgical Pathology and Pathology, Washington University School of Medicine, and Surgical Pathologist, Barnes Hospital and affiliated hospitals, St. Louis, Missouri.
2 Assistant Professor of Pathology, Washington University School of Medicine, and Surgical Pathologist, Barnes Hospital and affiliated hospitals.
1. Most well-differentiated tumors are capable of synthesizing the same products as the normal tissues from which they arise. However, the term "functioning tumor" usually refers to endocrine or nonendocrine tumors which produce hormones. Pathologic examination of functioning tumors requires fresh tissue which can be examined immediately after excision by electron microscopy, histochemistry and biochemical assay.
2. When tumors spread by direct invasion, they follow the path of least resistance so that certain structures will temporarily prevent local spread. Cancer may also be directly implanted by manipulation of the primary tumor. Biopsy and subsequent surgery should be planned so that possible areas of implantation (e.g., the tract of needle biopsy) will be excised with the tumor. Cancer of certain sites carries a very high risk of implantation and for the patient it is often best not to perform biopsy before surgery. The cancer surgeon must always take appropriate precautions against the possibility of tumor implantation in skin grafting and at suture lines.
The lymphatics are the most common pathway of cancer spread and careful dissection and microscopic examination of lymph nodes is very important in determining prognosis. Even the experienced cancer surgeon cannot evaluate involved nodes by palpation alone.
Vein invasion is a major mechanism of cancer spread and can be the most important single prognostic indication in certain types of cancer. Gross evidence of vein invasion is infrequent and microscopic evidence must be based on attachment of tumor to the wall of the vein, rather than on the presence of tumor cells alone.
3. The pathologist has a definite role in cancer radiotherapy. Radiotherapy should not be instituted until the tumor has been examined microscopically. The pathologist is also responsible for establishing criteria of radiosensitivity of a given type of tumor and assessing the effect of irradiation. There are three rules the pathologist uses to gauge the success of radiotherapy. 1. Study should be delayed until the therapy has taken effect. 2. The pathologist must be sure that tissue samples are adequate for accurate postirradiation examination. 3. Extreme care is necessary in determining the viability of irradiated tumor cells.
