The epigenetics of breast cancer family history

Breast cancer runs in families; however, genetic predisposition (such as being BRCA1 or BRCA2 mutation carriers) explains only a portion of this observation. Epigenetic changes (modifications in the genome that alter gene expression but do not affect the DNA sequence per se) have been shown to also play a role in breast cancer risk.

Researchers from the Columbia University Medical Center in New York have now examined whether a specific epigenetic modification (more specifically, methylation of the DNA) can be associated to breast cancer family history in unaffected women from high-risk breast cancer families.

This important work suggests that the levels of DNA methylation in white blood cells from cancer-free women could be one of the factors playing a role in the clustering of breast cancer in families with extensive cancer histories within its members.

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For the full Open Access report by Delgado-Cruzata et al. in the February 2014 issue of Epigenetics, visit the following link.

Epigenetics is a multidisciplinary peer-reviewed journal that publishes original research and review articles covering the latest findings about epigenetic mechanisms and their role in diverse biological processes. Established in 1997, Landes Bioscience is an Austin, Texas-based publisher of biology research journals and books.

Women with a strong family history of breast cancer have a higher risk for developing the disease compared to the wider population. A strong family history means having at least two close blood relatives (eg mother, sister, daughter, cousin or aunt) on the same side of the family (mother's or father's) affected by breast cancer, often with their diagnoses occurring at a young age (less than 50).

The higher risk can be associated with inherited factors -- specifically, the presence of mutations in genes associated with breast cancer. Two known genes are BRCA1 and BRCA2. It is thought that inherited mutations in genes such as these account for 5% to 10% of all breast cancer. Even though inherited gene mutations can play a part in breast cancer risk, there are women with a strong family history (and a higher risk) who do not carry known gene mutations.

It is also important to note that most women who get breast cancer do not have a strong family history. Women can sometimes over-estimate their risk based on family history.

For those concerned about their strong family history or hereditary aspects of breast cancer, the issues can be very complex and challenging. The decision to undergo a test, for example, can result in the need for unanticipated communication with family members. There may be financial implications for the women seeking tests as well as others in their families. There may be concerns and fears about the potential for discrimination by employers and insurers. Some women undergoing tests feel that science and technology have enabled them to answer questions about breast cancer in their families. Others find themselves asking even more questions and facing even more difficult decisions. For more on these issues and challenges, see our background paper.