Incidence of In Situ and Invasive Vulvar Cancer in the US, 1998-2003

BACKGROUND. The human papillomavirus (HPV) vaccine has been shown to prevent precancerous lesions of the vulva with the potential to prevent a percentage of vulvar cancers. To provide a baseline picture before HPV vaccine implementation, the authors described vulvar cancer epidemiology by age, race, ethnicity and histology in the US. METHODS. The authors examined incidence data from 39 population-based cancer registries that met high-quality data standards from 1998 to 2003, covering approximately 83% of the US population. They limited their analysis to in Situ and invasive vulvar squamous cell carcinomas (SCCs). In situ vulvar cancers did not include vulvar intraepithelial neoplasia type 3 (VIN 3). RESULTS. SCC accounted for 77% of in situ cases and 75% of invasive vulvar cancers, an annual burden of 1498 in Situ and 2266 invasive SCC vulvar cancers. Greater than 75% of the in situ and invasive SCCs had no specific histology identified. White women had the highest rates of vulvar cancer; the incidence rates of invasive vulvar SCC among black women and Hispanic women were approximately one-third lower than for their counterparts (white women and non-Hispanic women, respectively). For women aged <50 years, the age-specific rates of invasive SCC were approximately the same among whites and blacks. Increases in rates after age 50 years, however, were noted to be more rapid among white than among black women. CONCLUSIONS. Distinct age-specific incidence rate patterns of invasive vulvar SCC by race and ethnicity and the higher incidence rates observed among white women compared with women of other races and ethnicities were opposite to patterns noted for cervical cancer. Underestimations of the burden of in situ vulvar cancers were a result of the inability to examine VIN 3 in the authors' data. Encouragement of cancer registries to report and submit VIN 3 data and more research on data quality will allow a thorough assessment of the impact of HPV vaccine by providing a basis for examining the true burden and quality of these precancerous vulvar tumors. Increased documentation of histologic subtypes in pathology reports and in cancer registry data can help differentiate the burden of HPV-associated types from non-HPV-associated types of vulvar cancers. Cancer 2008;113(10 suppl):2865-72. Published 2008 by the American Cancer Society.*