Forty years later NEJM reflects on DES, an actual endocrine disruptor

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Forty years after publishing the groundbreaking study linking in utero diethylsilbestrol (DES) exposure to a rare vaginal cancer — clear-cell adenocarcinoma (CCA) — the New England Journal of Medicine (NEJM) has come out with a historical perspective piece on this incredible story. Over five decades ago, DES started off as a prescription drug to prevent miscarriages based on a single 1948 study. Subsequent studies failed to support its efficacy for maintaining pregnancy, but it was still widely prescribed — until a 1971 study revealed its ill effects.

This latter research demonstrated that females exposed to DES in utero have an estimated 1 in 1,000 to 1 in 10,000 incidence of developing CCA fifteen to thirty years later. Once grown up, these women were often subjected to multiple pelvic exams and lived in fear of developing cancer. They were also found to have twice the rate of miscarriages compared to non-DES-exposed women. The authors of the current NEJM piece reiterate that DES is a real endocrine disruptor, proven to cause significant alterations in the reproductive tract that have been well documented — unlike bisphenol A (BPA) or phthalates, trace chemicals often superficially referred to as "endocrine disruptors." Adds ACSH's Dr. Gilbert Ross, “In contrast to these chemicals, which have been widely and safely used for over 50 years without a single instance of death or injury, the large majority of DES-induced CCA cases were found within 20 years.”

“The DES story is an example of how identifying a true disease cluster actually works,” says ACSH's Dr. Elizabeth Whelan. “This was a genuine cluster because an investigation was able to establish a clear cause-and-effect relationship between DES and CCA. This is how epidemiology works best.”