Epidemiology of vulvar neoplasia in the NIH-AARP Study.

To clarify risk factors for rare vulvar neoplasms.

Within the NIH-AARP Study, among 201,469 women interviewed in 1995-1996 and followed for a mean of 13.8years, there were 370 diagnoses of incident vulvar neoplasms, including 170 invasive and 198 vulvar intraepithelial neoplasms grade 3 (VIN3). Hazard ratios (HR) and 95% confidence intervals (CI) were calculated via multivariate logistic regression for various demographic, reproductive and lifestyle factors, with separate consideration of relations according to invasiveness, histology and age at diagnosis.

Consistent with descriptive data, we found non-white women at lower risks of vulvar neoplasia than white women (HR=0.59, 95% CI 0.36-0.95). Significant risk factors for VIN3 included being divorced/separated (HR vs. currently married=1.77, 95% CI 1.24-2.51), a current cigarette smoker (3.88, 95% CI 2.64-5.72), a user of oral contraceptives (1.46, 95% CI 1.06-2.01), or a current user of menopausal hormones (1.73, 95% CI 1.24-2.41). Significant risk factors for invasive cancers were being obese (HR for BMI ≥30 vs. <25=1.62, 95% CI 1.10-2.40) or a current smoker (1.86, 95% CI 1.21-2.87). Cigarette smoking was a risk factor mainly for neoplasms shown in other investigations to be HPV-related, namely VIN3 and invasive squamous cell cancers (SCCs) occurring in the younger stratum of cases. In contrast, obesity was primarily associated with the development of invasive SCCs.

Our results support that vulvar neoplasia is a heterogeneous disease. VIN3 demonstrated risk factors consistent with an HPV-related etiology, while invasive cancers were additionally affected by obesity, suggesting that further attention should focus on the role of chronic inflammatory conditions.