Epidemiology of vulvar neoplasia in the NIH-AARP Study.

OBJECTIVE: To clarify risk factors for rare vulvar neoplasms.

METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.