A new study published in Nature Communications suggests that the risk of some familial breast cancers may be caused by a mother’s diet during pregnancy, and may not only affect the mother’s immediate offspring, but also may increase breast cancer risk to future generations.
Why is this study important?
Studies have already shown the link between a mother’s diet and its effects on the health of her children. But this research shows for the first time that a diet high in fat or excess estrogen can increase the risk of breast cancer in not only their daughters, but also for their granddaughters and great granddaughters. The study conducted by Georgetown’s Lombardi Comprehensive Cancer Center has demonstrated these results only on rats, but it strongly suggests directions for additional research.
How was the study conducted?
The researchers tested three groups of pregnant rats: one group was fed a diet high in fat before pregnancy and throughout pregnancy, a second group was fed a diet supplemented with estrogen in the last week of pregnancy, and the last group – the control group—was fed a normal diet. The group fed a diet high in fat had the risk of breast cancer increased by 55 to 60 percent in daughters and granddaughters, but the risk did not extend to the great-granddaughters. The group that was fed the supplemental estrogen had a 50 percent risk increase of breast cancer, and the risk did extend to the great-granddaughters in this group. Both groups also showed precancerous structural changes in the breast tissue of the affected offspring compared to the control group.
Are these adverse effects reversible?
Potentially. These risk factors eventually may be identifiable through blood tests, and certain drugs called HDAC and DNMT inhibitors may be able to turn on and off genes that have been affected by exposure.
What other environmental risk factors are there?
We know that inheriting changes to certain genes, such as BRCA1 and BRCA2, greatly increases the risk of breast cancer, and we also know that daughters whose mothers took the synthetic estrogen DES to reduce pregnancy complications have an increased risk of breast cancer. But there are also other environmental factors at play. There is a growing body of epidemiologic data on the association between exercise and breast cancer, showing lower risks for breast cancer with greater levels of physical activity.
Along with exercise, weight has also shown to have both a positive and negative effect on risk. Studies found that women who were overweight or obese had a 30 to 50 percent greater risk for post-menopausal breast cancer development than leaner women. In contrast, however, excess weight and obesity have also been associated with a lower risk of breast cancer developing during the pre-menopausal years. There also has been research confirming an association between moderate to heavy alcohol consumption and the risk of developing breast cancer.