Role of pelvic chemoradiation therapy in patients with initially metastatic anal canal cancer: A National Cancer Database review.
BACKGROUND: Although the management of localized anal canal squamous cell carcinomas is well established, the role of pelvic chemoradiation (CRT) in the treatment of patients presenting with synchronous metastatic (stage IV) disease is poorly defined. This study used a national cancer database to compare the overall survival (OS) rates of patients with synchronous metastatic disease receiving CRT to the pelvis and patients treated with chemotherapy (CT) alone. METHODS: This study included adult patients with anal canal squamous cell carcinomas presenting with synchronous metastases diagnosed from 2004 to 2012. Multiple imputation and 2:1 propensity score matching were used to create a matched data set for testing. The proportional hazards model was used to estimate the hazard ratio (HR) for the effect of the treatment group on OS. With only patients in the matched data set, the OS of the treatment groups was estimated with the Kaplan-Meier method by treatment group. RESULTS: This study started with an unmatched data set of 978 patients, and 582 patients were selected for the matched data set: 388 in the CRT group and 194 in the CT-alone group. The HR for the group effect was 0.75 (95% confidence interval [CI], 0.61-0.92; P = .006). The median OS was 21.1 months in the CRT group (95% CI, 17.4-24.0 months) and 14.6 months in the CT group (95% CI, 12.2-18.4 months). The corresponding 5-year OS rates were 23% (95% CI, 18%-28%) and 14% (95% CI, 7%-21%), respectively. CONCLUSIONS: In this large series analyzing OS in patients with stage IV anal cancer, CRT was associated with improved OS in comparison with CT alone. Because of the lack of prospective data in this setting, this evidence will help to guide treatment approaches in this group of patients.
Abdelazim, YA; Rushing, CN; Palta, M; Willett, CG; Czito, BG
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