Risk of anal cancer in a cohort with human papillomavirus-related gynecologic neoplasm.

OBJECTIVE: To assess the development of anal cancer in women diagnosed with a human papillomavirus-related cervical, vulvar, or vaginal neoplasm.
METHODS: Using data from National Cancer Institute's Surveillance, Epidemiology and End Results program from 1973 through 2007, 189,206 cases with either in situ or invasive cervical, vulvar, or vaginal neoplasm were followed for 138,553,519 person-years for the development of subsequent primary anal cancer. Standardized incidence ratios were calculated from the observed number of subsequent anal cancers compared with those expected based on age-, race-, and calendar year-specific rates in the nonaffected population.
RESULTS: Anal cancer developed in 255 women with a history of in situ or invasive gynecologic neoplasm, aggregate standardized incidence ratio of 13.6 (95% confidence interval [CI] 11.9-15.3), indicating a 13-fold increase in anal cancer compared with expected. The standardized incidence ratio for anal cancer incidence among women with in situ vulvar cancer was 22.2 (95% CI 16.7-28.4) and was 17.4 (95% CI 11.5-24.4) for those with invasive vulvar cancer. The standardized incidence ratio for anal cancer incidence in women with in situ cervical cancer was 16.4 (95% CI 13.7-19.2) and was 6.2 (95% CI 4.1-8.7) for women with invasive cervical cancer. The standardized incidence ratio for anal cancer incidence among women with in situ vaginal cancer was 7.6 (95% CI 2.4-15.6) and was 1.8 (95% CI 0.2-5.3) for invasive vaginal cancer.
CONCLUSION: Women with human papillomavirus-related gynecologic neoplasm are at higher risk for developing anal cancer compared with the general population. This high-risk population may benefit from close observation and screening for anal cancer.