[Cancer of the anal canal]

Anal carcinoma is a rare malignant tumor, It occurs in only 0.02% of all malignant neoplasms. In Mexico, the incidence is of 1.5%, and only 0.18% belong to the anal canal. In recent years it has been reported an increased incidence of this tumor due to the association with the human papilloma virus in HIV positive patients. The most common histological forms are the epidermoid and the cloacogenic carcinomas. The most relevant prognostic factors are the size of the tumor and the presence of lymph node metastasis. Surgery has been the traditional form of treatment but the combined use of chemotherapy and radiotherapy seems to have the best results and surgery is reserved for local recurrences or palliation. A review of our experience at the National Institute of Cancer at Mexico city with the management of this tumor was performed. Thirty-four patients with the diagnosis of carcinoma of the anal canal were included of which none of them received previous treatment or have the diagnosis of AIDS. Patients were divided in four groups according to the form of treatment (surgery, radiation, and chemoradiation either with 5FU-MMC or 5FU and CDDP). The group that received chemotherapy with 5FU and CDDP combined with radiotherapy had the best results in terms of clinical response, survival and toxicity. The size of the tumor and the presence of lymph node metastasis are the prognostic factors that influence in survival: tumor smaller than 5 cm without lymph node metastasis have the best prognosis (p: 0.01 and p: 0.00004). Epidermoid carcinoma have a better prognosis than cloacogenic carcinoma (p: 0.07).