Healthy lifestyle choices can help women overcome genetic breast cancer risk

Study by Johns Hopkins researchers could help improve prevention strategies

High risk breast cancer due to family history and genetics can be substantially mitigated by a healthy lifestyle choices, according to new research from the Johns Hopkins Bloomberg School of Public Health.

The study, published today in the journal JAMA Oncology, found that roughly 30 percent of breast cancer cases in white women in the U.S. could be prevented by modifying known risk factors—for example, drinking less alcohol, losing weight, stopping smoking, and not taking hormone replacement therapy. More importantly, a higher proportion of these preventable cases occur among women with genetic and family risk factors.

The researchers found that white women with the genetic and family risk factors who also practiced healthy lifestyles faced roughly the same breast cancer risk as an average white woman in the U.S. The average chance that a 30-year-old white woman will develop breast cancer before age 80 is about 11 percent.

Down the line, the research could contribute to precision prevention strategies for breast cancer, particularly as the price of genetic testing continues to dip into a more affordable range. The findings may also help scientists create better guidelines for breast cancer screenings based on individual risk factors.

The disease remains the most common form of malignancy diagnosed in women in Western developed countries, with an estimated 40,000 fatalities per year in the U.S.

"People think that their genetic risk for developing cancer is set in stone," says study senior author Nilanjan Chatterjee, a Bloomberg Distinguished Professor at the Bloomberg School. "While you can't change your genes, this study tells us even people who are at high genetic risk can substantially change their health outlook by making better lifestyle choices such as eating right, exercising, and quitting smoking."

Chatterjee and his colleagues developed a model for predicting breast cancer risk using thousands of health records from the Breast and Prostate Cancer Cohort Consortium and the National Health Interview Study. Researchers combined individual-level data on risk factors like age, weight, and smoking with data on almost 100 common gene variations known to combine to create significantly higher risk of breast cancer. These gene variations are quite different from the well-known rare mutations in BRCA1 and BRCA2, where a single variant can create a very high risk of breast cancer.

The findings are currently applicable only to white women because further research is needed to understand how genetic variants affect breast cancer risk for other ethnic groups.

Chatterjee says the model—though still several years away from being ready for routine medical use—could be helpful for finding a way to screen women who are at higher risk of breast cancer more often. Currently, screenings are mostly based on age, with the U.S. recommending routine mammograms starting at age 50.

"We aren't saying there will be less screening, just smarter screening," Chatterjee says.

Chatterjee also says he hopes that once women understand that their genes do not completely predict their cancer destiny, they will work harder to make lifestyle changes to reduce their odds with the disease.

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