Management of squamous cell carcinoma of the anus and adenocarcinoma of the lower rectum

Abstract

In the past, cancers of the lower most portion of the alimentary tract have required radical surgery to offer the patient a chance of cure. Unfortunately, for those lesions of the anus, a combined abdominal perineal resection was almost always necessary to remove the malignant neoplasm. This resulted in a permanent colostomy, which altered the patient’s anatomy and function of the bowel as far as evacuation was concerned. If this proved to be a necessary operation, then a colostomy was an acceptable procedure. It is unfortunate, however, when a colostomy has been performed that the pathologic findings are such that would indicate that a lesser operation or other treatment might have successfully and satisfactorily treated the cancer. For many years, squamous carcinomas of the perirectal region, that is, the area of skin from the anal verge to approximately 5 cm beyond the verge, have been identified early because they are on the exposed surface. These lesions have been treated by local excision and by radiation with excellent results. A 5-year survival rate in the range of 90% is usual. Squamous cell carcinoma and basaloid cell ‘carcinoma, both having about the same prognosis, more often were treated by radical resection because these lesions frequently were more advanced and there was always the risk of interference with sphincteric function by using a conservative procedure. This meant that the patient potentially would be incontinent, an unfortunate complication of local treatment. This, too, mea.nt that a combined abdominal perineal resection was preferred in many instances rather than the lesser procedure. Overall, when a squamous cell carcinoma was treated by a radical procedure, the survival rate was about 60% at 5 years and 40% at 10 years. When positive nodes were present, the 5-year survival rate dropped to 32%. Similar survival rates were anticipated in the management of basaloid squamous carcinoma. If either type of lesion was superficially invaded and if local treatment was judged satisfactory, the survival rate was in the range of 80 to 90%. The above figures represent the experience of the past. Today, with improved knowledge regarding the use of radiation therapy in many anatomic areas (in this instance to the anal area), and the availability of chemotherapy, it is becoming apparent that through these combined modalities, the neoplasm can be satisfactorily eliminated in many instances, without the necessity of carrying out a radical surgical procedure that leaves the patient with a colostomy. The success of combined modalities in the management of squamous cell cancer of the anus and also adenocarcinoma of the lower portion of the rectum is well demonstrated in the report by Doctor Sischy.’ The proof of the effectiveness of this approach to the problem is nicely demonstrated by the four patients in whom a subsequent combined abdominal perineal resection was carried out and no residual tumor was found in the surgical specimen. Even though this high success rate might not prove to be true in all cases, it does illustrate that this approach to the treatment of these lesions is successful and eliminates the need for a colostomy. If the approach to the problem should not prove successful in some cases, the lesions most likely will be reduced in size or kept under control during a period of time. If it is apparent that the lesion is not being totally destroyed by the combination therapy, then the radical surgical procedure can be carried out. It is unfortunate, however, that some of these lesions have spread distantly before diagnosis and the beginning of therapy; this is unfortunate because in time the distant metastasis most often will cause death of the patient. Although it does seem reasonable to consider procedures less radical than a combined abdominal perineal resection, it should be remembered that there is an error rate in the accurate staging of cancers at this anatomic site. For that reason, selection of treatment should be conservative for patients in whom there is some question as to whether the lesion might be more extensive than clinically evident.