Abstract
BACKGROUND: To examine the prognostic relevance of human papillomavirus (HPV) infection for anal squamous cell carcinoma (ASCC) patients treated with chemoradiation (CRT) in the National Cancer Data Base (NCDB). METHODS: The 2014 NCDB was queried for non-metastatic, histologically confirmed, ASCC patients diagnosed between 2004 and 2013. Patients were required to have HPV status documented in order to be eligible. Patients were then stratified into two groups: HPV+ and HPV-. Univariate analysis (UVA) was performed using the χ(2) test for categorical covariates and ANOVA for numerical covariates. Multivariable analysis (MVA) was performed using Cox proportional hazard model for overall survival (OS). Hazard ratios (HRs) and 95% confidence intervals (CIs) were generated for each covariate. To minimize selection bias, propensity score (PS) weighting was implemented to balance OS related variables between the groups including: age, education level, stage, diagnosis year, insurance type, and agent of chemotherapy. RESULTS: A total of 1,063 patients were eligible. Patients were stratified into HPV+ (n=498, 46.8%) and HPV- (n=565, 53.2%). After PS weighting, MVA for OS showed that for men, HPV infection was associated with better OS (HR: 0.60, 95% CI: 0.38-0.96; P=0.034). However, for women, HPV infection did not significantly influence survival (HR: 1.47, 95% CI: 0.96-2.25; P=0.074). CONCLUSIONS: To our knowledge, this is the largest patient series evaluating the impact of HPV infection on OS in patients with anal cancer. We found that HPV infection is associated with a statistically significant better survival for men with ASCC. In contrast, for women, HPV infection did not significantly influence survival.