Women who maintain certain "breast-healthy" habits can lower their risk of breast cancer, even if a close relative has had the disease, a new study finds.
Engaging in regular physical activity, maintaining a healthy weight and drinking alcohol in moderation, if at all, was shown in a large study to help protect against breast cancer in postmenopausal women, the researchers said.
"Whether or not you have a family history, the risk of breast cancer was lower for women engaged in these three sets of behavior compared to women who were not," said study leader Dr Robert Gramling, associate professor of family medicine at the University of Rochester Medical Center in New York.
The study was published in the journal Breast Cancer Research.
Gramling wanted to look at the effects of lifestyle habits on breast cancer risk because he suspects some women with a family history may believe their risk is out of their control.
He analysed data on US women aged 50 to 79 from the Women's Health Initiative study starting in 1993. During 5.4 years of follow-up, 1,997 women were diagnosed with invasive breast cancer.
Gramling excluded women with a personal history of breast cancer or with a family history of early-onset cancer (diagnosed before age 45), then observed the impact of the healthy habits.
Excluding those with an early-onset family history makes sense, because a stronger genetic (versus environmental) component is thought to play a role in early-onset, experts say.
How the study was done
Following all three habits reduced the risk of breast cancer for women with and without a late-onset family history. "For women who had a family history and adhered to all these behaviours, about six of every 1,000 women got breast cancer over a year's time," he said.
In comparison, about seven of every 1,000 women developed breast cancer each year if they had a late-onset family history and followed none of the behaviours.
Among women without a family history who followed all three habits, about 3.5 of every 1,000 were diagnosed with breast cancer annually, compared to about 4.6 per 1,000 per year for those without a family history who followed none of the habits.
For his study, Gramling considered regular physical activity to be 20 minutes of heart-rate raising exercise at least five times a week. Moderate alcohol intake was defined as fewer than seven drinks a week. A healthy body weight was defined in the standard way, having a body mass index, or BMI, of 18.5 to under 25.
Gramling hopes his research will reverse the thinking of women whose mother or sister had breast cancer who sometimes believe they are doomed to develop the disease, too.
The findings echo what other experts have known, said Dr Susan Gapstur, vice president of the epidemiology research programme at the American Cancer Society, who reviewed the study findings.
"The results of this study show that both women with a family history [late-onset] and without will benefit from maintaining a healthy weight and exercising, and consuming lower amounts of alcohol, limiting their alcohol consumption," she said.
The American Cancer Society guidelines for reducing breast cancer risk include limiting alcohol to no more than a drink a day, maintaining a healthy weight and engaging in 45 to 60 minutes of "intentional physical activity" five or more days a week.
The risk reduction effects found in the Gramling study may actually increase if women follow the more intense exercise guidelines of the ACS, Gapstur said.