Distribution of human papillomavirus genotypes in invasive squamous carcinoma of the vulva

Many studies have established a critical role for human papillomavirus (HPV) in the development of anogenital squamous neoplasia. In this report, we show the distribution of 37 high- and low-risk HPV types in 116 cases of invasive squamous vulvar carcinoma. Sections from paraffin-embedded tissue blocks were dissected as necessary to select areas of invasive carcinoma. Clinical and pathologic variables were analyzed using t-tests, univariate odds ratios and logistic regression analysis. Seventy percent of cases were HPV-positive, with an average patient age of 65 years (n = 81). HPV-negative cases (n = 35) had a higher average age (70 years), but these populations were not statistically different (t = 1.65, P = 0.10). HPV16 was most common (n = 65). Other HPV types were less frequent (HPV33, n = 12; HPV45, n = 4; HPV52 and 6, each n = 3; HPV18, 53 and 62, each n = 2). Additional HPV types were identified only once. Multiple infections typically included HPV16 (12/14 cases). Tumors showing low-risk HPV (11 cases) and low-risk HPV only (three cases) were uncommon. Regional node metastasis was documented in 29 of 116 tumors, and 8/9 HPV-positive nodes contained HPV types identical to the primary tumor. Of tumor types, warty carcinoma was most strongly associated with high-risk HPV (odds ratio 4.34, 95% confidence interval 1.32-18.45), particularly high- risk HPVs other than type 16 (odds ratio 9.04, 95% confidence interval 1.60-54.00). Tumors associated with any HPV type (odds ratio 0.40, 95% confidence interval 0.14-1.17), any high- risk type (odds ratio 0.36, 95% confidence interval 0.12-1.08), or type 16 alone (odds ratio 0.34, 95% confidence interval 0.11-1.12) were less likely to metastasize than HPV-negative tumors. Correcting for possible confounding variables, such as patient age and tumor histology, linear logistic regression analysis confirmed this association (high- risk HPV odds ratio 0.28, 95% confidence interval 0.09-0.89).