Epidermoid carcinoma of the anal margin: 17 cases treated with curative-intent radiation therapy.

Between 1973 and 1991, 17 patients with epidermoid carcinoma of the anal margin without evidence of distant metastasis were treated with curative-intent radiation therapy (RT). There were nine T1-tumors, six T2-, one T3- and one T4-tumor; two patients presented with inguinal node involvement: one N1 and one N3. Nine patients underwent prior incomplete local excision (six with microscopic involvement of surgical margins and two with macroscopic residual disease). The radiation dose to the tumor was 60-70 Gy; the radiation dose to the inguinal lymph nodes was 40-45 Gy in N0, and 50-60 Gy for involved inguinal nodes. The 5- and 10-year cancer-specific survival rates were 86.2% and 77.5%, respectively. The same probabilities were 100% and 100% for T1-tumors, 60% and 40% for T2-tumors. Severe complications occurred in two patients, one anal radionecrosis requiring a colostomy and one permanent anal incontinence after local excision, which was non-related to irradiation. For the cured patients, the sphincter preservation rate after 5 years was 82% (9/11). In univariate analysis and in Cox multivariate analysis, the cancer-specific survival rate was influenced by one factor: the tumor size.