Identification of Risk Factors for Diethylstilbestrol-associated Clear Cell Adenocarcinoma of the Vagina: Similarities to Endometrial Cancer

: This epidemiologic case-control study describes risk factors for clear cell adenocarcinoma of the vagina among 106 cases and 447 controls with in utero exposure to diethylstilbestrol (DES). Controlling for age, socioeconomic status, and time during gestation of initial DES exposure, the authors found a significantly increased risk of this cancer in women who were taller or more obese then their contemporaries at age 14-15 years. The relative risk of this cancer for women in the highest tertile for height compared with those in the lowest tertile was 2.5 (95% confidence interval 1.23-4.90). The relative risk from a similar comparison of body mass was 2.8 (95% confidence interval 1.20-6.53). Trend tests indicated that both factors had significant dose-response relations with risk of vaginal clear cell adenocarcinoma. These findings are particularly interesting since height and body mass are risk factors for endometrial cancer. DES-positive cases interviewed more than 10 years after diagnosis were also significantly thinner than cases interviewed less than 7 years after diagnosis (p = 0.01), providing the first evidence that adolescent adiposity level is associated with survival times for women with this disease.