Which statement about DES exposure is true?

• A. It has no health effects
• B. DES exposure is associated with cervicovaginal cancer risk
• C. It only occurs in females
• D. DES exposure reduces breast cancer risk

Answer: (B)

DES exposure in utero is linked to an increased risk of cancers of the cervix and vagina in female offspring, specifically the rare but well-described clear cell adenocarcinoma. This risk became evident after DES was used to prevent miscarriage for several decades, and what followed showed that the exposure disrupted development of the reproductive tract, leading to abnormalities and, later, cancer risk that can appear in adolescence or young adulthood.

It’s not true that DES has no health effects, since reproductive tract anomalies and cancer risk are well-documented outcomes. The exposure is not limited to females—females and males both carried the drug exposure in utero, though the most clearly established cancer risk is in daughters. And the idea that DES exposure reduces breast cancer risk isn’t supported; while maternal DES use has been studied for breast cancer risk with mixed findings, there isn’t a clear protective effect, and the question focuses on cancer risk in exposed offspring, where cervicovaginal cancer risk is the established concern.