Is the incidence of invasive vulvar cancer increasing in the United States?

Objective To document incidence rates of vulvar cancer, specifically invasive vulvar cancer, from 1973 to 2004 in the United States. Methods Nine US cancer registries from the Surveillance, Epidemiology, and End Results (SEER) databases were used to identify women aged 15-84 years, who were first diagnosed with vulvar cancer during 1973-2004. Age-adjusted incidence rates and annual percentage changes were calculated for different time periods, stage of the disease, age, race, and geographic area. Results During 1973-2004, the incidence of in situ vulvar tumors increased by an average of 3.5% per year (95% CI: 2.9%, 4.1%), while the incidence of invasive tumors increased 1.0% per year (95% CI: 0.6%, 1.4%). An increasing incidence was observed for localized and regional invasive tumors. To at least some degree, the rise of incidence rates of incidence tumors was evident in every age category, race, and geographic region. Conclusions Incidence rates of invasive vulvar cancer have increased in the United States during the last three decades. The reasons for this increase are unknown.