Is survival reduced for patients with anal cancer requiring surgery after failure of radiation? Analysis from a population study over two decades

Chemoradiotherapy is the standard treatment for anal cancer. Surgery is reserved for failure of therapy, but there are limited data examining outcomes after surgery. From a prospective population-based database on radiation and surgical therapy, we compare outcomes for patients with anal cancer undergoing rectal resection after radiation with patients undergoing radiation alone. Patients undergoing surgical resection of the rectum after initial radiation (SRT) for squamous cell carcinoma of the anus, anal canal, cloacogenic zone, and overlapping lesions of the rectum and anal canal from 1983 to 2002 were identified from the Surveillance, Epidemiology and End Results database. Patient and tumor characteristics of SRT were compared with those of patients who underwent radiation alone (RT). Survival was calculated by the Kaplan-Meier test. There were 1202 patients undergoing RT and 48 patients undergoing SRT. RT and SRT had similar median age, gender, and grade of tumor. SRT had more patients with regional stage of disease (66.7 vs 42.4%, P = 0.001). Mean survival for SRT was, however, similar to RT (103 vs 96 months, P = 0.8). For patients with localized stage, survival for SRT and RT was similar (105 vs 98 months, P = 0.7). For patients with regional stage, survival for SRT and RT was similar (95 vs 83 months, P = 0.6). The presence of regional disease appears to be associated with surgical resection after radiotherapy. Mean survival for such patients is comparable to that of patients undergoing radiation alone. Because radiation is combined with chemotherapy, this suggests that salvage surgery after failure of therapy results in outcomes comparable to combination therapy alone.