Lifestyle may matter even more when your DNA is working against you, research shows

WebMD News from HealthDay

By Amy Norton

HealthDay Reporter

THURSDAY, May 26, 2016 (HealthDay News) — Women who carry common gene variants linked to breast cancer can still cut their risk of the disease by following a healthy lifestyle, a large new study suggests.

In fact, lifestyle might be especially powerful for women at relatively high genetic risk of breast cancer, researchers found.

“Those genetic risks are not set in stone,” said senior researcher Nilanjan Chatterjee, a professor at Johns Hopkins Bloomberg School of Public Health in Baltimore.

The study found that four lifestyle factors were key: Maintaining a healthy weight; not smoking; limiting alcohol; and not using hormone therapy after menopause.

The researchers estimated that if all white U.S. women did those things, almost 30 percent of breast cancer cases could be avoided. And a majority of those averted cancers would be among women at increased risk because of family history and the gene variants they carry.

The study did not include women with the BRCA gene mutations that substantially raise the risks of breast and ovarian cancers.

Instead, it focused on 92 gene variants that, individually, would make only a small difference in a woman’s breast cancer risk.

But the variants are much more common than BRCA mutations, Chatterjee said. And their effects on breast cancer risk add up, he explained.

One question has been, how much does lifestyle matter for those women?

The answer: “Lifestyle factors may be even more important for women at higher genetic risk than for those at low genetic risk,” he said.

The findings were published online May 26 in JAMA Oncology. The results were based on records from more than 40,000 women tested for 24 gene variants previously linked to breast cancer risk.

Chatterjee’s team created a “model” for predicting a woman’s risk of breast cancer, using that genetic information plus other factors. Those other factors included ones that can’t be changed — such as family history of breast cancer and the age menstruation started — along with lifestyle habits.

The researchers then added one more element to the mix: They estimated the effects of 68 other gene variations that the women weren’t tested for.