Blood test could give early warning of breast cancer

July 2, 2014

In the future a simple blood test may indicate whether a woman is at higher risk of developing breast cancer. The test could offer many women an early warning even if they do not inherit genes linked to the disease.

Scientists have identified a molecular “switch” in blood samples that increases a woman's chances of having breast cancer. The “switch” is part of the process by which certain molecules acting on DNA cause genes to be turned on or off. The marker is associated with the BRCA1 breast cancer gene, but it was also found in women without the mutation who developed the disease.

About 10% of breast cancers are caused by BRCA1 and BRCA2 gene variants inherited from parents, leaving 90% of cases unexplained. A woman with the BRCA1 gene has an 85% risk of developing breast cancer. But until now there has been no reliable way of predicting the likelihood of non-inherited breast cancer.

Lead researcher Professor Martin Widschwendter, MD, University College London, says, “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.

The scientists analyzed blood sample DNA from 119 postmenopausal women who went on to develop breast cancer over a period of up to 12 years, and 122 women who remained cancer-free. The results appear in the online journal Genome Medicine. Read the study abstract.

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