The researchers said that the study may be significant because although family history is an important predictor of breast cancer risk, only a small number of genetic mutations have been identified, suggesting that other heritable in utero changes may be at play.
Previous research has suggested that in utero exposure to a range of hormone-disrupting chemicals and certain dietary factors could influence breast cancer risk across generations.
The study’s lead investigator, Georgetown Lombardi post-doctoral researcher Sonia de Assis, said: “We found that if the mother was fed a high-fat diet before conception and throughout pregnancy, the increased breast cancer risk was transmitted to granddaughters through either male or female germ-line.”
Incidence of breast cancer increased by 55 to 60% in the daughters and granddaughters of rats fed high fat diets during pregnancy, compared to those of rats on normal diets. The effects of the high fat diet were not passed on to great-grandchildren of the original rats.
Meanwhile, the daughters of rats given synthetic oestrogen had a 50% greater risk of breast cancer – and increased risk was passed down through three generations.
“This study suggests directions for future research in women,” de Assis says. “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 oestrogen, perhaps unwittingly, through the environment?”
The researchers said that the study could be a first step toward developing a blood test that could determine whether an individual was at high risk of breast cancer, which could be prevented by ‘turning off’ the responsible genes.
Source: Nature Communications
Vol. 3 Article number: 1053 doi:10.1038/ncomms2058
“High-fat or ethinyl-oestradiol intake during pregnancy increases mammary cancer risk in several generations of offspring”
Authors: Sonia de Assis, Anni Warri, M. Idalia Cruz, Olusola Laja, Ye Tian, Bai Zhang, Yue Wang, Tim Hui-Ming Huang & Leena Hilakivi-Clarke