Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement, Endocrine Reviews, 2009
Direct evidence of prenatal estrogen exposure and breast cancer risk is being gathered from the cohort of women born to mothers treated with DES during pregnancy and is discussed above (see Sections II and III).
These women are now reaching the age at which breast cancer becomes more prevalent.
In the cohort of these women who are aged 40 yr and older, there is a 2.5-fold increase in the incidence of breast cancer compared with unexposed women of the same age, suggesting that indeed, prenatal exposure to synthetic estrogens may play an important role in the development of breast neoplasms.
Consistent with this, experiments in rats showed that prenatal exposure to DES resulted in increased mammary cancer incidence during adulthood. These experiments illustrated that rats exposed prenatally to DES and challenged with the chemical carcinogen dimethylbenzanthracene (DMBA) at puberty had a significantly greater incidence of palpable mammary tumors at 10 months of age than animals exposed prenatally to vehicle. In addition, the tumor latency period was shorter in the DES-exposed compared with the vehicle-exposed group.
Both the epidemiological and experimental data are consistent with the hypothesis that excessive estrogen exposure during development may increase the risk of developing breast cancer.
In summary, exposure to estrogens throughout a woman’s life, including the period of intrauterine development, is a risk factor for the development of breast cancer. The increased incidence of breast cancer noted during the last 50 yr may have been caused, in part, by exposure of women to estrogen-mimicking chemicals that have been released into the environment from industrial and commercial sources. Epidemiological studies suggest that exposure to xenoestrogens such as DES during fetal development, to DDT around puberty, and to a mixture of xenoestrogens around menopause increases this risk.
- Full study (free access) : Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement, Endocrine Reviews, NCBI PubMed PMC2726844, 2009 Jun.
- Image credit pino naigro.