Even People With Breast Cancer Genes Can Lower Their Risk Of Developing It, Study Says

A recent study has revealed how much of a woman's risk of developing breast cancer might be in her control. The results suggest that even when women have a family history of the disease, they can be reduced if they lose weight and don't smoke.

According to Time Magazine, the study predicts that about 30 percent of breast cancer cases among white women may be prevented if all the women avoided four things: avoided smoking, drank very little alcohol, kept a healthy body weight and skipped hormone replacement therapy. Researchers said that these requirements held true even to those who were at a high risk for breast cancer due to family history and genetics.

Women at high risk who modified these risk factors had about the same chance of developing breast cancer over most of her lifetime as an average white woman in the United States without genetic vulnerability. That chance for a 30-year-old white woman is about 11% before she reaches age 80.

"Overall, we estimated that up to 28.9 percent of all breast cancers could be prevented if all white women in the U.S. population were at the lowest risk from these four modifiable risk factors," Nilanjan Chatterjee of the Johns Hopkins Bloomberg School of Public Health and colleagues wrote in their report, published in the Journal of the American Medical Association's JAMA Oncology.

Chatterjee quickly explained that the calculation is not ready for the average person to use yet. But he says the findings offer hope to people who may find out they have a "cancer gene" and feel they are doomed. "Lifestyle plays such an important role even in the context of genetic risk," he told NBC News.

In today's time, where DNA tests are becoming more common, easy to get done and coming down in price, more and more people will be able to find out if they have a rare mutation that raises their risk for cancer, explained Chatterjee. "There is so much in the news that everything is determined by genetic risk," he said.

His finding shows there is something people can do. And there's no risk to not smoking, keeping at a healthy weight, limiting drinking or avoiding HRT.

"It doesn't hurt anybody but what happens sometimes is that people lack motivation," Chatterjee said.

The team studied the cases of more than 40,000 women participating in breast cancer and other health studies. They looked at 92 common mutations known to raise breast cancer risk. They left out the two best-known breast cancer risk genes - BRCA1 and BRCA2 - because they're so clearly defined and studied. Chatterjee said his team wanted to inform thousands of women who don't have BRCA1 and BRCA2 mutations who find out they have other mutations that may raise their breast cancer risk. And he said these 92 common mutations, which women usually don't know about, account for more cases of breast cancer than the BRCA genes do.

"Our analysis shows that use of a model based on most known risk factors can change the recommendation for screening for a substantial fraction of the population, compared with using only age-based criteria," the team wrote.

They calculated that 16 percent of 40-year-old women have the breast cancer risk of someone 10 years older and might want to get mammograms earlier than recommended. And they said 32 percent of 50-year-old women have a lower-than-average risk for their age. "These women benefit least from screening and may benefit from additional counseling about risk of false-positive results," the team wrote.

However, the studies did not include women of different racial and ethnic backgrounds, so the scientists say that more research is needed to understand how breast cancer risk could be modulated with lifestyle behaviors among women from different race groups.

The latest findings are not the first to suggest the important role that healthy lifestyle changes can play in avoiding cancer. A different study found that lifestyle behaviors and environmental exposures account for between 20% and 40% of cancer, and another study found that people can reduce their risk of 13 kinds of cancer by 20% if they exercise regularly.