In situ and invasive vulvar cancer incidence trends (1973 to 1987)

OBJECTIVE: The objective of this study was to examine recent trends in the incidence of vulvar cancer. STUDY DESIGN: Cases of in situ and invasive squamous cell vulvar cancer were identified from nine Surveillance, Epidemiology, and End Results cancer registries. RESULTS: The incidence rate of in situ vulvar cancer nearly doubled between 1973 to 1976 and 1985 to 1987, whereas the rate of invasive squamous cell carcinoma remained relatively stable. CONCLUSIONS: Possible reasons for this discordance include the following: (1) Women affected by the "sexual revolution" are not yet old enough to have invasive vulvar carcinoma; (2) early diagnosis and treatment of in situ carcinoma have mitigated anticipated increases in invasive vulvar carcinoma incidence; (3) in situ and invasive carcinomas of the vulva have different etiologies, with the sexually transmitted human papillomavirus involved in the etiology of in situ carcinoma and other factors involved with most invasive squamous cell carcinoma.