DES Exposure Linked to Breast Cancer in Mothers, Daughters

<"">DES (diethylstilbestrol) may increase breast can risks for DES Daughters, as well as their mothers. DES, a synthetic form of estrogen, was used to treat between 5 and 10 million pregnant women from 1938 and 1971. These women, along with an estimated 2 million DES Daughters are believed to be at risk for breast cancer because of their exposure.

DES was widely prescribed to prevent premature delivery and miscarriage. When given during the first 5 months of a pregnancy, DES can interfere with the development of the reproductive system in a fetus. Use of DES declined – but did not stop – following studies in the 1950s that showed it was not effective in preventing pregnancy complications.

In 1971, the Food & Drug Administration (FDA) issued a Drug Bulletin advising physicians to stop prescribing DES to pregnant women. The FDA warning was based on a study published in 1971 that identified DES as a cause of a rare vaginal cancer called clear cell adenocarcinoma in girls and young women who had been exposed to DES before birth. Since then, DES has been linked to even more disorders, and even now, more than three decades after the FDA issued its DES warning, all of the health consequences of DES exposure are not known.

One of those ailments is breast cancer. Until recently the majority of DES Daughters were too young to determine whether DES exposure increased their risk of breast cancer. However, a recent study provides initial results linking exposure to DES before birth with increased rates of breast cancer (Palmer, 2002). The study found that among study participants, DES Daughters were more likely to experience breast cancer than were unexposed women. DES Daughters had a relative risk of 1.4 (40% higher incidence of breast cancer). However, the finding was not statistically significant, which means that the increased rate of breast cancer could have been the result of chance.

The study did find that, in study participants over 40, DES Daughters were two-and-a-half times more likely than unexposed women to be diagnosed with breast cancer. The results for women over 40 were statistically significant (not likely to be due to chance). DES Daughters under 40 years of age did not experience an increased risk of breast cancer. The increased risk association was present for all breast cancer risk factors examined, and did not differ by tumor receptor status, tumor size, or lymph node involvement.

According to the National Cancer Institute, 16 percent of women prescribed DES during pregnancy developed breast cancer, in comparison with 13 percent of women not prescribed DES. Therefore, it is estimated that one in six women who were prescribed DES will develop breast cancer, whereas one in eight women in the general population will develop the disease.

Many people are not aware that they were exposed to DES. Women who think that they or their mothers were exposed to DES can contact the attending physician or the hospital where the delivery took place to request a review of the medical records. The Centers for Disease Control’s DES Update website also provides a Self-Assessment Guide featuring a series of questions designed to help individuals assess their likelihood of DES exposure.

Legal help for DES Daughters and Mothers who suffer from breast cancer and other health problems is available at <"">

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