Cumulative Risk of Second Primary Cancers in Women with Index Primary Cancers of Uterine Cervix and Incidence of Lower Anogenital Tract Cancers, Michigan, 1985–1992

Abstract

A retrospective cohort study of women with cancers of the lower anogenital tract was derived from the Michigan Tumor Registry records for the years 1985–1992. Incidence rates of invasive cervical, vulvar, vaginal, and anal cancers were analyzed with respect to age, race, year of diagnosis, stage at diagnosis, and histopathology. The incidence of metachronous primary cancers following initial primaries of the cervix was also investigated. Anogenital cancers constituted about 4% of all cancers in Michigan women between 1985 and 1992. Age-adjusted incidence rates per 100,000 women per year for each site were found to be as follows: 10.1 (cervix), 1.9 (vulva), 1.0 (vagina), and 0.6 (anus). The incidence rates of women in the United States for cancers in the anogenital region were higher in blacks than in whites, with the exception of vulvar cancer. U.S. blacks were more likely to develop squamous cell carcinomas, but less likely to develop adenocarcinomas of the cervix and vagina when compared to whites. Over the 5- to 8-year follow-up period, 6.5% of the women with index cases of cervical cancer developed second primary cancers. This represented a 40% increase in the risk of incident primary cancers compared to the risk in the general population of Michigan women. The significant occurrence of second primaries of the vagina following index primaries of the cervix suggests a shared etiology, such as infection with human papillomavirus. The incidences of cancers related to smoking, including cancers of the urinary bladder, lung/bronchus, and lower anogenital tract were also increased.