Prognostic Significance of P16INK4a Expression in Penile Squamous Cell Carcinoma: A Meta-Analysis with Trial Sequential Analysis

Background. Recently, P16INK4a expression has been shown to be correlated with cancer-specific survival (CSS) in penile squamous cell carcinoma (SCC). Therefore, we performed this meta-analysis to clarify the prognostic value of P16INK4a for penile SCC. Methods. A systematic search was performed in PubMed, Embase, and Web of Science to identify all relevant articles up to May 25, 2017. Hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of included studies were pooled to estimate the prognostic value. Trial sequential analysis (TSA) was performed to assess the quantity and strength of survival evidence. Results. Five retrospective studies consisting of 323 cases were finally included. We found that P16INK4a positive expression was significantly associated with a better CSS of penile SCC (HR=0.45, 95%CI: 0.30-0.67, P