Prognostic value of tumor regression evaluated after first course of radiotherapy for anal canal cancer

Purpose: To evaluate whether the tumor response after an initial course of irradiation predicts for colostomy-free survival and overall survival in patients with anal canal cancer. Methods and Materials: Between 1980 and 1998, 252 patients were treated by pelvic external-beam radiotherapy (EBRT) followed by a brachytherapy boost in 218 or EBRT in 34. EBRT was combined with chemotherapy in 168 patients. An evaluation of tumor regression, before the boost, was available for 221 patients. They were divided into four groups according to the tumor response: 80% but Results: The median follow-up time was 58 months. The overall survival rate was 72.6% ± 3.1% and 57.3% ± 4.2% at 5 and 10 years, respectively. The disease-free survival rate was 60.0% ± 3.3% and 49.4% ± 3.9% at 5 and 10 years, respectively. The colostomy-free survival rate was 61% at 5 years and 47% at 10 years. Two groups could be differentiated according to the percentage of tumor regression before the boost: >80% vs. ≤80%. The group with a T3-T4 lesion and tumor regression ≤80% had the poorest overall (52.8% ± 12.3%), disease-free (19.9% ± 9.9%), and colostomy-free survival (24.8% ± 11.2%) rates. Conclusion: The amount of tumor regression before EBRT or brachytherapy boost is a strong prognostic factor of disease control without colostomy. When regression is ≤80% in patients with an initial T3-T4 lesion, the use of conservative RT should be carefully evaluated because of the very poor disease-free and colostomy-free survival.