TIME Health Cancer Heres How Well Your Genes Can Predict Your Breast Cancer Risk Researchers say genetic sequencing can predict breast cancer risk better than previously thought

Your genes have a lot to say about who you are and how healthy you are. But for certain diseases, including cancer, so many genes are likely involved that its hard for doctors to come up with a useful, reliable way to turn your DNA information into a precise risk score.

But in a paper published in the journal Cancer Epidemiology, Biomarkers & Prevention, researchers say that combining the known genetic players in breast cancer can predict with much higher accuracy a newborn girls theoretical risk of developing the disease.

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Alice Whittemore, a professor of epidemiology and biostatistics at Stanford University School and Medicine, and her colleagues included 86 known genetic variants that have been associated with breast cancerincluding BRCA1 and BRCA2, which are relatively rare but confer a very high risk of disease compared to those that have a smaller contributionand created a computer model that took into account the rates of breast cancer among 120,000 women who had these genetic variants.

This model served as a predictor for breast cancer based on womens genetic makeup. When researchers looked at the top 25% of risk scores, they found that these would account for about half of breast cancer cases in the future. Using previous models, genetic variants could account for only 35% of future cancer cases.

Our results are more optimistic than those that have been previously published, says Whittemore, because we took 86 known genetic variants associated with breast cancer, and took what was in the worlds literature about how common those variants are, and by how much a factor they increase risk. And the more genetic variants that are identified, the better we will get at this.

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Since the paper was submitted, several new genetic variants have been linked to breast cancer, and adding those to the model, says Whittemore, could make it more effective.

But just because a woman may have been born with a high genetic risk for breast cancer doesnt mean that she cant change that risk. The model found that lifestyle factors, which are in a womans control, can generally lower the genetic risk by half. And the higher a womans genetic risk, the more she can reduce it with healthy behaviors. So avoiding excessive amounts of alcohol and smoking, or maintaining a healthy weight, for example, can bring a genetic risk of 30% down to around 15%, while a woman with a 4% genetic risk of developing breast cancer can reduce her risk by 2%.

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Heres How Well Your Genes Can Predict Your Breast Cancer Risk