THE CHANGING ROLE OF THE SURGICAL ONCOLOGIST - 06/09/11
Resumen |
The role of the surgical oncologist in management of cancers generally is changing because of the many changes in clinical disease presentation on the basis of screening and earlier diagnosis and in light of new understandings about the biologic behavior of various cancers. A continual flood of basic and clinical research threatens to overwhelm the surgical oncologist. Surgical oncologists traditionally have been trained and are experienced in the application of radical surgical procedures, such as pelvic exenteration, abdominoperineal resection, limb amputation for sarcomas, abdominosacral resection, liver resection, and esophagogastric resections for cancers of the distal esophagus and proximal stomach. They also have been taught an appreciation of the need to correlate the extent of surgical procedure with the nature and risk of the primary tumor. This balanced view that relates the extent of the surgical procedure to the danger of the cancer is increasingly necessary because many cancers appear at earlier stages in the rectum and colon, breast, thyroid, head, and neck and as melanomas and sarcomas.
It is important to keep in mind, however, the basic principles in surgical oncology,9 which govern four areas: (1) local tumor excision, (2) regional lymph node removal, (3) the handling of local or regional recurrence, and (4) the possibility of surgical resection of distant metastases.
Local excision accomplishes several important functions while not affecting others. Local excision removes the local cancer and its symptoms and potential complications. Thus, resection of an ulcerated carcinoma of the colon with potential for an obstruction can stop the bleeding and prevent future complications from bowel obstruction. Removal of a local breast cancer prevents further local growth and the possibility of ulceration, bleeding, symptoms, and mass. The local removal of the cancer also completes the assessment of prognostic information about the patient's future by enabling simple clinical measurements, such as size, grade, and extent, and also provides more sophisticated prognostic information, such as the biochemical, genetic, and hormonal features of the primary cancer. The local removal also helps to prevent local recurrence, which may perpetuate or reinstitute the complications of local disease in the patient's future. Furthermore, the local removal stops the systemic leakage of cancer cells that have the potential for causing further distant metastases. Local removal, however, does nothing about the many cancer cells that left the primary site before removal. The patient's future is established at the time of the local removal because, for the most part, distant metastases are what govern survival outcome in cancer patients, and the systemic spread of cells already has been determined at the time of the local removal.
Regional lymph node removal, of course, eliminates nodal metastases if they are present and provides significant prognostic information, because, despite all the comprehensive biologic tests currently at the surgical oncologist's disposal, the presence of lymph node metastases still ranks as the most important prognostic information that can be obtained. By understanding the number, extent, and type of lymph node metastases, further sophistication in prognostication can be achieved. Finally, the removal of regional lymph node metastases prevents regional recurrence, which uncommonly may produce palliative problems in the future of the patient if not controlled.
The application of surgical procedures can help solve problems of local and regional recurrence by removal of disease at that later phase, improve the patient's quality of life, provide further prognostic information, and prevent future symptoms and complications. More radical surgical procedures to remove the primary cancer more widely or the lymph nodes more radically for the prevention of local recurrence or the prevention of regional node recurrence, however, do not increase cure rates nor govern the survival of the patient.8, 9 The later appearance of lymph node metastases or recurrence and local recurrence and the rapidity of their appearance provide further prognostic information and are indicators of patient outcome, but do not control that outcome in a causative way.19 More and more radical local procedures never have been shown to improve the survival of patients and more and more radical lymphatic resections again have not been shown to improve the survival possibilities of patients.2, 5, 17 Furthermore, adjuvant local radiation therapy does not increase survival although it usually decreases local recurrence.17 The ability to prevent local recurrences most be kept in the context of the overall goals for the patient in terms of functional and cosmetic results. The realization that excessive measures to prevent local or regional recurrence in a few patients may involve excessive surgery or other local or regional measures in most patients and this balance must be constantly kept in mind to provide the most good for the largest number.
Finally, the surgical treatment of distant metastases contributes little to overall cancer control. Only in the few instances in which distant metastases are confined to a single organ site in patients with other favorable prognostic features of the distant metastatic presentation does surgical removal provide any chance of cure. The rapidity of discovering distant metastases has no bearing on survival; the curability of surgical resection of distant metastases is a pattern-dependent function, not a time-dependent phenomenon. No program of early detection of distant metastases has been shown to improve cure rates. In liver resections of colorectal carcinomas metastatic to that organ, the pattern of the metastatic appearance (three or fewer nodules) controls the possibility of survival, not how rapidly or quickly the metastases themselves are discovered by surveillance. Thus, the curability is not related to size or time of discovery, but is related to biologic features of the original cancer (node metastases and stage) and the distant metastasis itself (level of carcinoembryonic antigen (CEA) at presentation of liver metastasis).
A similar philosophy applies to pulmonary resections in sarcomas and the more uncommon possibility of pulmonary resection or isolated organ resection of the patient with melanoma. Few other metastatic sites, although apparently isolated at the time of discovery, lend themselves to or are accompanied by the possibility of long-term disease-free survival. If such situations occur, they should be pursued vigorously, but not searched for deliberately. It is incumbent for the surgical oncologist to separate the need for palliation of symptoms from the potential for cure in metastatic sites more importantly than in the surgical approach to primary sites. A resection of an advanced primary cancer in the presence of distant metastases occasionally may be justified to solve severe symptomatic palliative issues of bleeding, infection, pain, or obstruction; almost never is such an aggressive approach warranted in a distant metastasis, which is accompanied by disease outside the metastatic organ site in question.
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| Address reprint requests to Blake Cady, MD, Breast Health Center, Women and Infants Hospital, 101 Dudley Street, Providence, RI 02905, e-mail: BCady@WIHRI.ORG |
Vol 80 - N° 2
P. 459-469 - avril 2000 Regresar al número
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