Local immune response depends on p16INK4a status of primary tumor in vulvar squamous cell carcinoma

Background: The p16(Ink4a) is not a surrogate marker for high-risk human papilloma virus (HPV) genotypes but indicates better prognosis in vulvar squamous cell carcinoma patients. Our recent study confirmed substantial mismatch between p16(Ink4a) and high-risk HPV-status as well as revealed that p16(Ink4a)-overexpression itself is an independent prognostic factor for vulvar cancer. Aim: To determine significance of the tumor infiltrating immune cells and p16(Ink4a)-status for better outcome of patients with vulvar cancer. Methods: Intraepithelial tumor infiltrating lymphocytes: CD8+, CD4+, FOXP3+, CD56+, tumor associated macrophages: CD68+, and GZB+ cells were calculated in 85 vulvar squamous cell carcinomas with previously defined p16(Ink4a) and high-risk HPV-status. Number of intraepithelial CD8+, CD4+, FOXP3+, CD56+, CD68+ and GZB+ cells were compared between tumors with different p16(INK4a) status and overlapping high-risk HPV-status separately. Survival analyses included the Kaplan-Meier method, log-rank test and Cox proportional hazards model. Results: p16(Ink4a)-negative tumors were more infiltrated by intraepithelial CD8+, CD4+ and GZB+ cells than p16(Ink4a)-positive tumors (p=0.032, p=0.016 and p=0.007 respectively). High-risk HPV-status did not correlate with the infiltration of immune cells. Median follow up was 89.20 months (range 1.7-189.5). High CD4+ and CD56+ indices were correlated with prognosis in p16(Ink4a)-positive cases (p=0.039 and p=0.013 respectively). Low CD68+ infiltrates were correlated with prognosis in p16(Ink4a)-negative cases (p=0.018). Conclusion: p16(Ink4a)-status impacts local immune surveillance as represented by tumor infiltrating immune cells. Immunologic effects contributing to clinical outcome might depend on p16(Ink4a)-overexpression.