Prenatal exposure to BPA, DES may boost breast cancer risk

Fetuses exposed to chemicals like Bisphenol-A (BPA) and Diethylstilbestrol (DES) in the womb may have a higher risk of developing breast cancer in their adulthood, according to a study published in the current issue of Hormones and Cancer. 

The study, led by researchers at Yale School of Medicine, showed exposure of pregnant mice to BPA or DES led to an increase in the level of a protein called EZH2 in their offspring.  

The protein controls the expression of all genes; higher EZH2 levels are associated with an increased risk of breast cancer in humans. 

"These results show that all estrogens, even weak ones, can alter the development of the breast and place our children at risk," said Hugh S. Taylor, M.D, lead author of the study. 

Taylor and colleagues said BPA is a weak estrogen and DES is a strong estrogen and both have a great impact on the gene expression in the breast throughout life. 

"The data, coupled with our data on DES and BPA effects on the uterus, clearly demonstrate a lasting effect of prenatal exposure to estrogens on the breast and uterus," Taylor added. 

"This study generates important safety concerns about exposures to environmental endocrine disruptors, such as BPA, and suggests a potential need to monitor women exposed to these chemicals for the development of breast lesions as adults." 

DES is a synthetic nonstreroidal estrogen that was indicated to reduce the risk of pregnancy complications and losses from about 1940 to 1970. The chemical was found in 1971 to cause a rare vaginal tumor in girls and young women. The FDA subsequently withdrew DES from use in pregnant women, according to wikipedia. 

DES was also used as a growth hormone in the beef and poultry industry in the 60s. It was phased out in the late 1970s after the chemical was found to cause cancer. 

Bisphenol A is commonly present in household products including plastic bottles, reusable food containers, and food cans. 

A review article published online May 25 in Nature Reviews Endocrinology finds that endocrine-disrupting chemicals like bisphenol A found in plastic pose cancer risk in adults. 

Drs. Carlos Sonnenschein and Ana Soto from Tufts University say in their report that the cancer causing effect is additive and is expected to manifest in a person's adulthood. 

Dr. Soto and colleagues on Dec 8, 2006 published a study in Reproductive Toxicology showing that exposure of female fetuses to bisphenol A may likely increase their breast cancer risk in adulthood. 

Breast cancer is diagnosed in more than 175,000 people in the United States; the disease kills about 50,000 annually in the country.

Jimmy Downs and editing by Rachel Stockton