Robert Hoover discusses diethylstilbestrol: its history and the long-term health effects
Since 1992, DCEG and other NCI investigators, along with collaborators from five field study centers, have been actively following diethylstilbestrol (DES) exposed and unexposed mothers, daughters and sons, and granddaughters for adverse health effects resulting from this exposure. As DES-exposed offspring are currently reaching the age when cancer rates begin to rise, it is important to continue to monitor long-term risk of cancer and other adverse health outcomes in this unique population. The study also provides a model for assessing a number of hypotheses that address concerns about prenatal hormonal influences on disease risk, both an intriguing area of science and an increasingly controversial environmental issue that affects a substantial proportion of the population.
To date the study has identified excess female breast cancer after age 40 that shows a dose-response effect, as well as increased risk for high-grade lesions of the cervix and vagina. Concern over other hormone-related cancers remains; though to date analyses have been limited due to small numbers of cases. In the sons, investigators observed an excess risk for urogenital anomalies and infertility, and a likely excess of testicular cancer. To examine the effects in the third generation (the daughters of the prenatally exposed daughters), investigators assembled a small cohort in 2000. Given their average age, there have been few relevant disease outcomes. However, investigators noted an elevated risk for infertility—though not statistically significant, this outcome was also seen in DES-daughters. In addition, there were three cases of ovarian cancer in the granddaughters, even though substantially less than one had been expected. While both of these observations remain difficult to interpret, they have added some urgency to expand the cohort and continue to follow-up.