What is the effect of diethylstilbestrol (DES) exposure in utero on breast cancer risk?

Updated: Dec 16, 2019
  • Author: Jessica Katz, MD, PhD, FACP; Chief Editor: Marie Catherine Lee, MD, FACS  more...
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Diethylstilbestrol, known as DES, was used clinically to prevent complications of pregnancy. In the late 1960s, an unusual occurrence of a rare cancer of the vagina among young women, called clear cell adenocarcinoma (CCA), was observed and subsequently linked to their intrauterine exposure to DES and in 1971, DES was removed from the market by the US Food and Drug Administration. However,  5 to10 million pregnant women and babies had been exposed to the drug. DES daughters have been found to have an increased risk for late breast cancer (~1.8-fol).

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