Impact of Facility Volume on Outcomes in Patients With Squamous Cell Carcinoma of the Anal Canal: Analysis of the National Cancer Data Base

BACKGROUND: Given the rarity of anal cancer and the technical aspects involved in radiation (RT) planning, the authors conducted a population-based analysis evaluating the impact of radiation oncology facility volume on overall survival (OS) in patients with squamous cell carcinoma (SCC) of the anal canal. METHODS: The National Cancer Data Base (NCDB) was queried for patients with SCC of the anal canal who underwent RT. All patients were coded as having received their entire course of RT at the NCDB reporting facility. Facility volume was categorized into tertiles (low, intermediate, and high) and was based on the number of times a facility's unique identification code appeared. RESULTS: In total, 13,550 patients were identified. Patients who received treatment at higher volume radiation oncology facilities had longer OS based on multivariate analysis (MVA) (hazard ratio, 0.81; 95% confidence interval [CI], 0.73-0.90; P < .001) and propensity score matching analysis (hazard ratio, 0.79; 95% CI, 0.69-0.91; P < .001). For patients who received treatment at low-volume, intermediate-volume, and high-volume centers, the 5-year OS rate was 70%, 72.2%, and 75.4%, respectively (P < .001). Compared with low/intermediate-volume radiation oncology centers, high-volume centers were more likely to treat patients with concurrent chemotherapy (odds ratio, 1.27; 95% CI, 1.07-1.51; P=.006) and less likely to have treatment delays leading to an RT duration of >45 days (odds ratio, 0.74; 95% CI, 0.69-0.80; P < .001). CONCLUSIONS: Treatment at higher volume radiation oncology centers appears to be associated with improved OS in patients with SCC of the anal canal. These results likely reflect the relation between physician experience and delivery of high-quality RT, which perhaps is best evident in rare tumors such as anal SCC. (C) 2016 American Cancer Society.