Influence of human papillomavirus and p16INK4a on treatment outcome of patients with anal cancer

BACKGROUND: The purpose of this study was to evaluate HPV-DNA and p16(INK4a) (p16) expression as prognostic markers for outcome in patients with anal cancer. METHODS: From January 2000 to December 2011 a cohort of 105 anal cancer patients was treated with definitive chemoradiation at our institution. Tumor biopsies from 90 patients were analyzed for HPV-DNA by polymerase chain reaction and for p16 expression by immunohistochemistry. RESULTS: Median follow-up was 48.6months (range 2.8-169.1months). HPV-DNA or p16-expression was found in 75 anal cancers each (83.3%), concordance was detectable in 70 tumors (77.8%). Significantly improved overall survival (OS) [77.1% vs. 51.4%, p=0.005], progression-free survival (PFS) [64.0% vs. 35.0%, p<0.001] and improved local control [81.0% vs. 55.9%, p=0.023] was found for concomitant HPV- and p16-positive anal carcinomas (cHPPAC) in univariate analysis. Multivariate analysis showed better OS [p=0.015] and PFS [p=0.002] for cHPPAC. CONCLUSION: The combination of HPV-DNA and p16 can be used as an independent prognostic parameter in anal cancer patients.