Surgery and chemotherapy are associated with improved overall survival in anal adenocarcinoma: results of a national cohort study

Purpose: Anal adenocarcinoma (AAC) is a rare disease with treatment protocols that mimic both that of rectal adenocarcinoma (RAC) and anal squamous cell carcinoma (ASCC). Due to its rarity, data regarding outcomes are lacking. We sought to determine outcomes of patients with AAC compared to RAC and ASCC and to evaluate risk factors for mortality in AAC. Methods: The United States’ National Cancer Database was queried for all adult patients presenting with nonmetastatic AAC, RAC, or ASCC from 2003 to 2011. The primary outcome was overall survival. Intergroup univariate comparisons, unadjusted Kaplan-Meier, and multivariable Cox proportional hazards modeling were used to compare outcomes between AAC, RAC, and ASCC and to identify factors associated with survival within AAC. Results: The query identified 129,153 patients (N = 2117 AAC, 19,427 ASC, 107,609 RAC). AAC patients were less likely than RAC patients to have surgery (72.5 vs. 87.1%), and also less likely to receive chemotherapy (54.7% vs. 96.1%) and radiation (58.2% vs. 74.1%) than patients with ASCC (all p < 0.001). Overall median survival in AAC was 65 months compared to 109 months for RAC and > 120 months for ASCC. On multivariable analysis, independent treatment-related predictors of decreased mortality hazard in AAC included proctectomy (hazard ratio [HR], 0.66) and chemotherapy (HR, 0.60) (both p < 0.001). Conclusion: AAC tumors have worse prognosis than either RAC or ASCC. Within patients with AAC, nonsurgical management was independently associated with increased mortality hazard. Patients with AAC should be evaluated in a multidisciplinary setting and referred for surgery.