CA: A Cancer Journal for Clinicians, Vol 29, 130-143, Copyright
© 1979 by American Cancer Society
The Pathology of Tumors Part IV: Behavior and Therapy of Tumors
Juan Rosai M.D1 and
Lauren V. Ackerman M.D.2
1 Professor, Laboratory Medicine and Pathology and Director of Anatomic Pathology, Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, Minnesota.
2 Professor of Pathology, State University of New York, Stony Brook, New York.
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 non-endocrine tumors that produce hormones. Pathologic examination of functioning tumors requires fresh tissue that can be examined immediately after excision by electron microscopy, histochemistry, immunohistochemistry, and biochemical assay.
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 in these instances it might be better 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 [See Fig. 20. in Source Pdf.] [See Fig. 21A and B. and 22A and B. in Source Pdf.] 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.
The pathologist has a definite role in cancer radiotherapy and chemotherapy. These forms of cancer treatment 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 post-irradiation examination.
3. Extreme care is necessary in determining the viability of irradiated tumor cells.
