30 Gy may be an adequate dose in patients with anal cancer treated with excisional biopsy followed by combined-modality therapy

Background and Objectives: There are a subset of patients with invasive anal cancers who undergo an excisional biopsy either before or after combined-modality therapy (CMT). The objective of this study is to determine whether these patients can be adequately treated with a lower dose of pelvic radiation therapy. Methods: A total of 25 patients were treated with CMT either before or after an excisional biopsy. The four subsets included 8 patients with initial excision followed by CMT with 30-34 Gy (EX/30), 6 patients with initial excision followed by CMT with 45-50.4 Gy (EX/45), 10 patients treated by CMT with 30 Gy followed by an excision (30/EX), and 1 patient by CMT with 45 Gy followed by an excision (45/EX). Results: For the total group, the actuarial 5-year disease-free survival was 78%, overall survival was 86%, colostomy-free survival was 91%, and local control was 82%. When patients received CMT either before or following an excision, the actuarial local control and survival results with 30-34 Gy vs. 45-50.4 Gy were similar. In contrast to radiation dose, in patients who received 30-34 Gy, the sequence of the excision (before or after CMT) did appear to have a borderline significant impact on local control. Actuarial 5-year local control was 100% for EX/30 vs. 67% for 30/EX (P = 0.08). Conclusions: Because of the small number of patients in each group and the retrospective nature of the analysis, it is difficult to draw definitive conclusions from this study. However, our data suggest that in patients who are selected to undergo an initial excisional biopsy followed by CMT, 30 Gy may be an adequate radiation dose. Local control may be higher in patients who undergo an excisional biopsy followed by CMT compared with the converse.