Long-term health risk for DES daughters revealed

Reported by Susan Aldridge, PhD, medical journalist

Daughters of women who used diethylstilbestrol in pregnancy run an increased risk of breast cancer.
Diethylstilbestrol (DES) is a synthetic estrogen that was used to prevent miscarriage in the 1940s and 1950s. A trial in 1953 showed it not to be effective but it was still used. Then girls born to mothers who had used DES developed rare cancers of the vagina and cervix. Now a long term study shows that these women, now in their 40s and 50s, are more prone to breast cancer compared to those not exposed to DES.

The National Cancer Institute study shows that DES daughters over age 40 have 1.9 times the risk of breast cancer and those over 50 have an even higher risk. Therefore those who know they have been exposed to DES need to have regular mammograms. They also need to be cautious about taking extra estrogen in the form of hormone replacement therapy. This is the first study to provide direct evidence that prenatal exposure to estrogen is a risk factor for breast cancer, although it is not clear yet how this may happen.

Source
Cancer Epidemiology. Biomarkers & Prevention August 2006