Twenty-five-year experience with radical chemoradiation for anal cancer.

Purpose: To evaluate the prognostic factors, patterns of failure, and late toxicity in patients treated with chemoradiation (CRT) for anal cancer.

Methods And Materials: Consecutive patients with nonmetastatic squamous cell carcinoma of the anus treated by CRT with curative intent between February 1983 and March 2008 were identified through the institutional database. Chart review and telephone follow-up were undertaken to collect demographic data and outcome.

Results: Two hundred eighty-four patients (34% male; median age 62 years) were identified. The stages at diagnosis were 23% Stage I, 48% Stage II, 10% Stage IIIA, and 18% Stage IIIB. The median radiotherapy dose to the primary site was 54 Gy. A complete clinical response to CRT was achieved in 89% of patients. With a median follow-up time of 5.3 years, the 5-year rates of locoregional control, distant control, colostomy-free survival, and overall survival were 83% (95% confidence interval [CI] 78-88), 92% (95% CI, 89-96), 73% (95% CI, 68-79), and 82% (95% CI, 77-87), respectively. Higher T stage and male sex predicted for locoregional failure, and higher N stage predicted for distant metastases. Locoregional failure occurred most commonly at the primary site. Omission of elective inguinal irradiation resulted in inguinal failure rates of 1.9% and 12.5% in T1N0 and T2N0 patients, respectively. Pelvic nodal failures were very uncommon. Late vaginal and bone toxicity was observed in addition to gastrointestinal toxicity.

Conclusions: CRT is a highly effective approach in anal cancer. However, subgroups of patients fare relatively poorly, and novel approaches are needed. Elective inguinal irradiation can be safely omitted only in patients with Stage I disease. Vaginal toxicity and insufficiency fractures of the hip and pelvis are important late effects that require prospective evaluation.