Risk of benign gynecologic tumors in relation to prenatal diethylstilbestrol exposure.We investigated the association between prenatal DES exposure and benign gynecologic tumors among women participating in the DES collaborative follow-up study. A total of 85 cases of uterine fibroids and 168 cases of ovarian or paraovarian cysts were confirmed by medical records. After adjustment for age, no association was found between prenatal DES exposure and ovarian cysts or uterine fibroids. DES daughters had 2-3 times the risk of being diagnosed with paraovarian cysts, which are cysts that originate from remnants of the Mullerian ducts and are located near the ovary and fallopian tubes. Paraovarian cysts are not known to cause any health problems.
We recommend caution when interpreting the results for paraovarian cysts. First, the pathologist making the initial diagnosis was not blinded as to the patient's exposure status. Therefore, the pathologist's knowledge of a patient's DES status may have influenced the recording of cysts, particularly those that have little clinical significance (e.g., paraovarian cysts), which in the absence of such exposure history were often not recorded. Second, the lining of the Mullerian duct derives from coelomic epithelium, as does the covering of the ovary from which epithelial cysts arise. It is unlikely that DES exposure would be associated with an increase in cysts of Mullerian origin (e.g., paraovarian), but not of ovarian epithelial origin (e.g., cystadenomas). Thus, greater incidental detection of paraovarian cysts among DES daughters, or more likely the absence of recording in non-exposed daughters, could have produced the positive association observed in our study.