A blood test could predict a patient's risk of developing breast cancer even when the high-risk BRCA1 mutation is not present.

Researchers found an epigenetic signature in the blood of women who are predisposed to breast cancer due to an inherited genetic mutation of the BRCA1 gene, a University College London news release reported.

Epigenetic alterations are believed to be key molecular switches that lead to the development of cancer. The same signature was found in women without a BRCA1 mutation who still developed breast cancer, meaning it could be a potential marker for women's breast cancer.

The BRCA1 mutation is inherited from either parent and is believed to be behind at least 10 percent of breast cancers. The cause of the remaining 90 percent of breast cancer is non-mutation carriers has not yet been discovered. Researchers are starting to understand that genetic mutations are not the only contributors to cancer development. They are now looking at epigenetics, which is the arrangement of gene expression. One of the most studied epigenetic processes is called DNA methylation.

To make their findings the researchers looked at blood samples collected several years before the breast cancer developed in two women cohorts.

 "We identified an epigenetic signature in women with a mutated BRCA1 gene that was linked to increased cancer risk and lower survival rates. Surprisingly, we found the same signature in large cohorts of women without the BRCA1 mutation and it was able to predict breast cancer risk several years before diagnosis," Professor Martin Widschwendter, the study's lead author and Head of University College London's Department of Women's Cancer said in the news release.

The team found changes in the epigenome of immune cells are key to cancer progression.

 "The data is encouraging since it shows the potential of a blood based epigenetic test to identify breast cancer risk in women without known predisposing genetic mutations," Widschwendter said.