Troisi R, et al. - Researchers investigated whether prenatal diethylstilbestrol (DES) exposure impacts estrogen metabolism, with a focus on reproductive hormone concentrations and metabolic pathways, in postmenopausal women (40 exposed, 20 unexposed) who were participants in the National Cancer Institute (NCI) Combined DES Cohort Study, had never used hormone supplements or been diagnosed with cancer, had responded to the most recent Cohort Study questionnaire, and lived within driving distance of Boston University Medical School. As per the initial findings, postmenopausal women who were prenatally DES exposed, vs those not exposed, may have relatively less 2 than 16 pathway estrogen metabolism. An association of lower 2 pathway metabolism with increased postmenopausal breast cancer risk has been observed; this could potentially provide a partial explanation for the modest increased risk observed for prenatally DES exposed women.