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

Background: 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.

Methods: 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.

Results: 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).

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