Background: There remains a lack of consensus regarding the optimal treatment for patients with curable adenocarcinoma of the anal canal (AAC). We sought to determine the role of definitive surgical resection and radiation in a large cohort of patients with AAC.
Materials and methods: We queried the Surveillance, Epidemiology, and End Results (SEER) registry to identify all patients with nonmetastatic AAC from 1988 to 2004 and analyzed clinical factors, treatment modalities, and overall survival in this cohort. Kaplan-Meier survival curves were constructed to compare 5-year overall survival based on treatment groups: abdominal perineal resection (APR) only, APR and external beam radiation (APR and EBR), and EBR only. We performed a Cox regression analysis to determine factors predictive of outcome.
Results: A total of 165 patients were identified with nonmetastatic AAC. Of these, 30 patients were treated with an APR only, 42 patients with an APR and EBR, and 93 patients with EBR only. The 5-year survival for APR only, APR and EBR, and EBR only was 58%, 50%, and 30%, respectively. The difference in survival was statistically significant (APR vs. EBR, P = .02; APR and EBR vs. EBR, P = 0.04). Multivariate analysis completed on 86 patients in this cohort confirmed that factors accounting for the survival differences included age (P = 0.004), nodal stage (P = 0.001), and treatment groups (P = 0.03). The hazard ratio between EBR only compared with APR only was 2.78.
Conclusions: Definitive surgical treatment in the form of an APR with or without EBR is associated with improved survival in patients with AAC.