Definitive radiotherapy for squamous cell carcinoma of the anal canal.

Purpose: To review the outcomes of definitive radiotherapy (RT) alone or combined with chemotherapy (CT) in the treatment of squamous cell carcinoma of the anal canal.

Methods: Between November 1968 and June 2005, 69 patients were treated with curative intent at the University of Florida. Distribution according to T stage was: T1, 11 (16%); T2, 29 (42%); T3, 21 (30%); and T4, 8 (12%). Distribution according to N stage was: N0, 53 (77%); N1, 3 (4%); N2, 7 (10%); and N3, 6 (9%). RT consisted of external beam RT (EBRT) in 30 patients (43%) and EBRT plus brachytherapy in 39 patients (57%). Thirty-eight patients (55%) received adjuvant CT: mitomycin C and fluorouracil, 21 patients (30%); cisplatin plus fluorouracil, 16 patients (23%); and other, 1 patient (1%). Median follow-up for all patients was 7.9 years (range: 0.1-17.3 years). One patient who was disease-free was lost to follow-up at 129 months.

Results: The 5-year local control rates were: T1, 100%; T2, 93%; T3, 70%; T4, 88%; and overall, 86%. The 5-year regional control rates were: N0, 96%; N1 and N2, 89%; N3, 100%; and overall, 96%. The 5-year colostomy-free survival rates were: T1, 82%; T2, 89%; T3, 65%; T4, 38%; and overall, 74%. The 5-year cause-specific and overall survival rates were: stage I, 100% and 64%; stage II, 86% and 70%; stage III, 80% and 76%; and overall, 87% and 71%, respectively. Seven patients (10%) developed Radiation Therapy Oncology Group grade 3 late complications and 4 additional patients (6%) experienced grade 4 late complications. A fatal acute complication occurred in 1 patient (1%).

Conclusion: The likelihood of cure and colostomy-free survival after EBRT alone or combined with brachytherapy is relatively high and likely improved by adjuvant CT. The acute toxicity of treatment is significant; the major risk is neutropenia and sepsis. Patients with advanced T4 cancers that result in sphincter dysfunction requiring a pretreatment colostomy will usually have a permanent colostomy.