Mothers who eat fatty foods while pregnant may increase the risk of breast cancer among their daughters and granddaughters.

Experts from Georgetown University have shown through tests on mice that high-fat diets or an overabundance of estrogen may result in a higher risk of breast cancer for coming generations of females in the family.

The research, which was published in Nature Communications, has revealed that “familial” breast cancers arise from genetic alterations stemming from what mothers eat while they are pregnant, because their eating habits affect the fetus, as well as the fetal germ cells – which can, in turn, raise the mammary-cancer risk in coming generations.

Leena Hilakivi-Clarke, professor of oncology at Georgetown Lombardi Comprehensive Cancer Center, commented:

“We know that maternal diet can have long lasting effects on an offspring’s health, but this study demonstrates, for the first time, that excess estrogens and a high-fat diet can affect multiple generations of a rat’s offspring, resulting in an increase in breast cancer not only in their daughters, but granddaughters and great granddaughters.”

Dietary overconsumption of estrogen has been found to lead to epigenetic changes in the breast tissue, which makes it more susceptible to cancer later in life, according to the team.

Hilakivi-Clarke explained that two-thirds of inherited breast cancers do not have known genetic mutations. High-fat diets and overconsumption of estrogens are clearly risk factors for generations to develop breast cancer.

Lead author of the study, post-doctoral researcher Sonia de Assis, commented:

“This study could translate into important health implications. Fatty foods are endemic in our society, and significant levels of substances that have hormonal activity similar to estrogens, called endocrine disrupting chemicals, have been found in food and drinking water.”

The scientists, from Finland and the United States, experimented with 2 different groups of pregnant rats and their babies. The first group was given high-fat diets, while the other was given a surplus amount of estrogens. The researchers compared the two groups to a control group of rats that were not given high fat diets or excess estrogen.

Assis commented: “We found that if the mother was fed a high-fat diet before conception and throughout pregnancy, the increased breast cancer risk transmitted to granddaughters through either male or female germ-line.”

The rats that were fed large amounts of estrogen had a 50% increased prevalence of tumors of the breast in their daughters, granddaughters and great-granddaughters – in comparison with the control group. The scientists found that the breast cancer risk was only passed through females.

The researchers are optimistic about the fact that the inheritance of breast cancer risk, due to family history, may be able to be found through blood tests, and therefore, stopped or reversed.

Hilakivi-Clarke continued: “Our ongoing preclinical studies have found that the increase in breast cancer risk caused by in utero exposure to excess estrogens can be reversed by drugs that reverse epigenetic marks – chemical modifications that turns genes on and off – caused by the exposure.”

Assis concluded:

“This study suggests directions for future research in women. Could a woman’s susceptibility to breast cancer development be determined by what her grandmother ate when she was pregnant, or whether she was exposed to high levels of estrogen, perhaps unwittingly, through the environment?”

Written by Christine Kearney