2013 Study Abstract:
Women are using estrogens for many purposes, such as to prevent pregnancy or miscarriage, or to treat menopausal symptoms. Estrogens also have been used to treat breast cancer which seems puzzling, since there is convincing evidence to support a link between high lifetime estrogen exposure and increased breast cancer risk. In this review, we discuss the findings that maternal exposure to the synthetic estrogen diethylstilbestrol during pregnancy increases breast cancer risk in both exposed mothers and their daughters. In addition, we review data regarding the use of estrogens in oral contraceptives and as postmenopausal hormone therapy and discuss the opposing effects on breast cancer risk based upon timing of exposure. We place particular emphasis on studies investigating how maternal estrogenic exposures during pregnancy increase breast cancer risk among daughters. New data suggest that these exposures induce epigenetic modifications in the mammary gland and germ cells, thereby causing an inheritable increase in breast cancer risk for multiple generations.
2013 Study Conclusion:
Women use estrogens for many purposes. During pregnancy, synthetic strogen DES was used to prevent miscarriage and promote healthy pregnancy, although it turned out to cause the opposite. During the reproductive years when a woman’s own estrogen levels are high, women use synthetic estrogens as contraceptives. Since estrogens play an important role in normal physiological functions in women, some menopausal and postmenopausal women use estrogen supplementation to regain the benefits of natural estrogens.
The effects of estrogens on breast cancer risk differ depending upon when during a woman’s life time they are used. Maternal exposure to DES during pregnancy increases breast cancer risk in mothers and their daughters. The adverse effects of synthetic estrogen exposure during pregnancy may not be limited to mothers and their daughters. Our preclinical study in rodents showed that maternal exposure to EE2 increases breast cancer risk in daughters, granddaughters, and great granddaughters. The first generation of OCs increased breast cancer risk at the time women were taking them, but the increase in risk was not permanent. The current, third generation contraceptives do not increase breast cancer risk. Menopausal and postmenopausal HT, if it contains both estrogens and progestin, increases a woman’s breast cancer risk, and recent data suggest that tumors developing during therapy are more aggressive than those in women not using HT. Estrogen-only HT does not increase breast cancer risk, and might even reduce it. However, due to other adverse effects of estrogen-only HT, it is not recommended beyond using it to control the most severe menopausal symptoms.
We are beginning to understand how the increase in breast cancer risk following in utero exposures to synthetic estrogens occurs. It most likely involves long-term epigenetic changes in genes that are important in determining the risk for breast cancer development, such as tumor suppressor genes, PcTGs and oncogenes. Briefly, an exposure to synthetic estrogens during the fetal period induces modifications in the epigenetic reprogramming of the genome, leading to changes in mammary gland morphology, and gene and protein expression. Some of these changes are transient, such as an increase in the number of TEBs in rodents, and some persist, such as an altered gene and protein expression involving tumor suppressor genes and oncogenes. Together, epigenetically induced modifications in the mammary gland morphology and gene expression increase the likelihood that environmental carcinogens and radiation induce malignant transformation, and evetually breast cancer. The next challenge is to determine whether the increase in risk can be reversed by reversing epigenetic changes that occur as a consequence of early life exposure to synthetic estrogens.
Additional Information : Exposures to Synthetic Estrogens at Different Times During the Life, and Their Effect on Breast Cancer Risk, Springer, Journal of Mammary Gland Biology and Neoplasia, Volume 18, Issue 1, March 2013, Special Issue: Environmental Risk Factors. Full text on NCBI PMC3635108.
More DES DiEthylStilbestrol Resources
- DES studies on cancers and screening.
- DES studies on epigenetics and transgenerational effects.
- DES studies on fertility and pregnancy.
- DES studies on gender identity and psychological health.
- DES studies on in-utero exposure to DES and side-effects.
- DES studies on the genital tract.
- Papers on DES lawsuits.
- DES videos and posts tagged DES, the DES-exposed, DES victims.