Time-dose considerations in the treatment of anal cancer.

PURPOSE: To analyze the impact of patient and treatment parameters in concurrent chemoradiation treatment for anal carcinoma. METHODS AND MATERIALS: Retrospective review of 50 MO anal cancer patients treated from 1984-1994. Most patients received concurrent 5-FU, mitomycin, and radiation. Local control and disease-free/overall survival were determined and analyzed according to patient and treatment parameters. RESULTS: With 43 month median follow-up, projected overall survival is 66% at 5 and 8 years. Disease-free survival is 67% at 5 years and 59% at 8 years. Local control is 70% at 5 and 8 years. Doses of > or =54 Gy are associated with improved 5-year survival (84 vs. 47%, p = 0.02), disease-free survival (74 v. 56%, p = 0.09), and local control (77 vs. 61%, p = 0.04). Although local control, disease-free survival, and overall survival were improved in patients whose overall treatment time was <40 days, this was not statistically significant. Outcome in the four patients with pretreatment hemoglobin (Hgb) <10 appeared worse with 3-year overall survival 50 vs. 68% (p = 0.07), disease-free survival 0 vs. 67% (p = 0.11), and local control 0 vs. 74% (p = 0.05). Projected 5-year overall survival, relapse-free survival, and local control in 4 HIV(+) patients is 0, 75, and 75%. Multivariate analysis reveals that dose (p = 0.02) and Hgb (p = 0.05) independently affect local control, dose (p = 0.02) affects disease-free survival, and dose (p = 0.01), Hgb (p = 0.03), T-stage (p = 0.03), and HIV-status (0.07) independently influence overall survival. CONCLUSION: Radiation doses of > or =54 Gy are associated with significantly improved survival and local control in anal cancer patients treated with chemoradiation. Overall treatment times of less than 40 days are associated with a trend towards improved outcome, but this is not significant. Pretreatment hemoglobin <10 is associated with worse treatment outcome. Survival of HIV (+) patient is poor, but the majority of such patients in this series died of intercurrent disease with their anal carcinomas controlled by chemoradiation.