Rare anal canal cancers in the U.S. veteran: patterns of disease and results of treatment.

Nationwide treatment results among U.S. veterans with rare anal cancers (AC) have not been previously reported. We sought to evaluate the demographics and treatment outcome of patients with rare AC in Veterans Affairs Medical Centers (VAMCs). Using national VA computer data sets, we identified all patients with the ICD-9 diagnostic code (154.2) for anal cancer from 1987-1991. Patient demographics, histopathology, tumor size, results of treatment, and survival data were sought from local tumor registrars. A total of 405 patients with AC were identified by computer search; 204 (51%) were evaluable. 164 (80%) had squamous cell carcinomas, 25 (13%) had basaloid carcinomas, 8 (4%) had melanomas and 7 (3%) had anal gland adenocarcinomas. Patients were treated either by local excision, abdominoperineal resection (APR), or primary chemoradiation. Mean follow-up was 5.1 years. Among 25 patients with basaloid tumors, 19/25 were treated with chemoradiation; 13/19 (68%) are alive, and 3/5 treated with radical surgery are living. Among the seven patients with adenocarcinoma, those treated with CR fared better than those who underwent APR. Among the 8 patients with melanoma, 3/7 (38%) underwent primary APR, and 5 (62%) were treated by local excision; 7/8 died. Rare anal tumors account for 20 per cent of all anal canal cancers in the VA population. Patients with basaloid tumors respond well to chemoradiation. Patients with anal melanoma continue to have a poor prognosis.