Does human papillomavirus infection imply a different prognosis in vulvar squamous cell carcinoma?

Two independent pathways in the development of vulvar squamous cell carcinoma (VSCC) have been described, one related to and the other independent of high-risk human papillomavirus (HR-HPV). The aim of our study was to evaluate whether the HPV status has a prognostic significance or can predict response to radiotherapy.

All VSCC diagnosed from 1995 to 2009 were retrospectively evaluated (n=98). HPV infection was detected by amplification of HPV DNA by PCR using SPF-10 primers and typed by the INNO-LIPA HPV research assay. p16(INK4a) expression was determined by immunohistochemistry. Disease-free and overall survival (DFS and OS) were estimated by Kaplan-Meier analysis with the log-rank test and a multivariate Cox proportional hazard's model.

HR-HPV DNA was detected in 19.4% of patients. HPV16 was the most prevalent genotype (73.7% of cases). p16(INK4a) stained 100% HPV-positive and 1.3% HPV-negative tumors (p<.001). No differences were found between HPV-positive and -negative tumors in terms of either DFS (39.8% vs. 49.8% at 5 years; p=.831), or OS (67.2% vs. 71.4% at 5 years; p=.791). No differences in survival were observed between HPV-positive and -negative patients requiring radiotherapy (hazard ratio [HR] 1.04, 95% confidence interval [CI] .45 to 2.41). FIGO stages III-IV (p=.002), lymph node metastasis (p=.030), size ≥ 20 mm (p=.023), invasion depth (p=.020) and ulceration (p=.032) were associated with increased mortality but in multivariated only lymph node metastasis retained the association (HR 13.28, 95% CI 1.19 to 148.61).

HPV-positive and -negative VSCCs have a similar prognosis. Radiotherapy does not increase survival in HPV-positive women.