Benign and Malignant Outcomes in the Offspring of Females Exposed In Utero to Diethylstilbestrol (DES): An Update from the NCI Third Generation Study.

Simple Summary: Females prenatally exposed to diethylstilbestrol have an elevated risk of severe cervical dysplasia and some cancers, while testicular cancer is increased in males. We assessed these associations in the prenatally exposed female's offspring (third generation). Based on third-generation females' self-reports, diethylstilbestrol exposure was not associated with risks of overall cancer, breast cancer, or severe cervical dysplasia. Borderline ovarian cancer risk in exposed vs. unexposed was elevated but compatible with chance. Based on mothers' reports, diethylstilbestrol exposure did not increase the risk of overall or other cancers in third-generation females. Overall cancer risk in exposed males appeared elevated but compatible with chance. Testicular cancer risk was not elevated in exposed males, and there were no prostate cancers reported. These data do not provide evidence that diethylstilbestrol is associated with cancer risk in third-generation females or males. The third generation is relatively young and requires follow-up to assess risk as the cohort ages. Background: Females exposed prenatally to diethylstilbestrol (DES) have an elevated risk of cervical dysplasia, breast cancer, and clear cell adenocarcinoma (CCA) of the cervix/vagina. Testicular cancer risk is increased in prenatally exposed males. Epigenetic changes may mediate the transmission of DES effects to the next ("third") generation of offspring. Methods: Using data self-reported by third-generation females, we assessed DES in relation to the risk of cancer and benign breast and reproductive tract conditions. Using data from prenatally DES-exposed and unexposed mothers, we assessed DES in relation to cancer risk in their female and male offspring. Cancer risk was assessed by standardized incidence ratios (SIR) and 95% confidence intervals (CI); the risks of benign and malignant diagnoses were assessed by hazard ratios (HR) and 95% CI. Results: In self-reported data, DES exposure was not associated with an increased risk of overall cancer (HR 0.83; CI 0.36–1.90), breast cancer, or severe cervical dysplasia. No females reported CCA. The risk of borderline ovarian cancer appeared elevated, but the HR was imprecise (3.46; CI 0.37–32.42). Based on mothers' reports, DES exposure did not increase the risk of overall cancer (HR 0.80; CI 0.49–1.32) or of other cancers in third-generation females. Overall cancer risk in exposed males appeared elevated (HR 1.41; CI 0.70–2.86), but the CI was wide. The risk of testicular cancer was not elevated in exposed males; no cases of prostate cancer were reported. Conclusions: To date, there is little evidence that DES is associated with cancer risk in third-generation females or males, but these individuals are relatively young, and further follow-up is needed. [ABSTRACT FROM AUTHOR]