Incidence of squamous neoplasia of the cervix and vagina in women exposed prenatally to diethylstilbestrol (United States)

Objectives: Women exposed prenatally to diethylstibestrol (DES) have an exc ess risk of clear-cell adenocarcinoma of the vagina and cervix, but the eff ect on the incidence of squamous neoplasia is uncertain. The purpose of the current study was to evaluate the long-term risk of developing high-grade squamous neoplasia of the genital tract among women exposed prenatally to D ES. Methods: A cohort comprising 3899 DES-exposed and 1374 unexposed daughters was followed for 13 years (1982-1995) for pathology-confirmed diagnoses of high-grade squamous intraepithelial neoplasia (HSIL) of the genital tract. Poisson regression analysis was used to compute relative risks (RR) and 95% confidence intervals (95% CI), adjusting for age, calendar year, and other covariates. Results: The RR (95% CI) among DES-exposed versus unexposed, based on 111 c ases of high-grade disease, was 2.1 (1.2-3.8). Adjustment for screening his tory estimated by the number of years since the last Pap smear had little e ffect. Risk estimates were higher with earlier intrauterine exposure; the R R (95% CI) for exposure within 7 weeks of the last menstrual period was 2.8 (1.4-5.5). Only two cases of invasive squamous cervical cancer occurred in total, precluding separate analysis. Conclusions: The findings support an association between in-utero DES expos ure and high-grade squamous neoplasia, although a role for more intensive s creening among DES-exposed women in the production of this excess could not be completely ruled out.