Prognostic Relevance of HPV Infection and p16 Overexpression in Squamous Cell Anal Cancer

Abstract

Purpose: Human papillomavirus (HPV) DNA and p16 status have both been reported as prognostic factors in anal cancer, but the prognostic relevance of combined detection and particularly HPV-/p16+ and HPV+/p16- signatures is unknown. We evaluated combined HPV DNA and p16 status as a prognostic factor of treatment response in anal cancer.

Methods: 106 patients treated with radiochemotherapy (RCT+5-FU/MMC) with available paraffin-embedded tumor tissue specimens were evaluated regarding local control (LC) and overall survival (OS) at 5 years. In addition to HPV DNA/p16 status, the influence of age, gender, previous surgery, initial recurrence, T stage, N status, and tumor localization was analyzed.

Results: 63 patients were HPV+/p16+, 9 were HPV+/p16-, 11 were HPV-/p16+, and 23 were HPV-/p16-. In univariate analysis, LC was significantly better in patients with T1/2 stage, female gender, and HPV/p16 status. HPV+/p16+ was associated with significantly better LC (88.1%; 95% confidence interval [CI]: 78.89-97.31) compared with HPV-/p16+ (63.6%; 95% CI: 35.18-92.02; P=.021) and especially HPV-/p16- (55.8%; 95% CI: 33.46-78.14; P=.002) but not with HPV+/p16- (77.8%; 95% CI: 50.56-105.04; P=.270). OS was influenced by T stage and LC. HPV+/p16+ patients showed a trend toward better OS compared with HPV-/p16- patients (HPV+/p16+: 81.1%; 95% CI: 70.12-92.08 vs HPV-/p16-: 68.8%; 95%CI: 47.44-90.16; P=.138). On multivariate analysis, T3/4 stage and HPV/p16 status (HPV-/p16+, HPV-/p16- vs HPV+/p16+) predicted poorer LC (T3/4: 50.3% vs T1/2: 86.6%, hazard ratio [HR] 0.22; 95% CI: 0.09-0.53; P<.001; HPV+/p16+ vs HPV-/p16+: HR 4.73; 95% CI: 1.33-16.82; P=.016, and HPV+/p16+ vs HPV-/p16-: HR 6.40; 95% CI: 2.23-18.35; P<.001), whereas local relapse dramatically influenced OS.

Conclusion: Our data suggest that HPV/p16 signature determines prognosis. HPV+/p16+ patients had the best prognosis, and HPV-/p16+ and HPV-/p16- patients showed the worst outcome and therefore require therapy optimization, particularly given that LC is the most important factor for OS.