U. ROCHESTER (US) — Regular physical activity, maintaining a healthy weight, and drinking less alcohol lowers breast cancer risk for women with, and without, a family history of the disease.
The finding is good news for women who have a close relative with breast cancer and thus fear that no matter what they do, it won’t matter, says Robert Gramling, associate professor of family medicine and community and preventative medicine at the University of Rochester.
Details of the study appear online in the journal Breast Cancer Research.
“It’s important to note that a family history of breast cancer can arise in part due to shared unhealthy behaviors that have been passed down for generations,” Gramling says.
“Untangling the degree to which genes, environments, and behaviors contribute to the disease is difficult. But our study shows that engaging in a healthy lifestyle can help women, even when familial predisposition is involved.”
Gramling analyzed data from the Women’s Health Initiative Observational Study that began in 1993 and included women ages 50 to 79.
Women with a personal history of breast cancer or with a close relative with early-onset (before age 45) breast cancer were excluded from the study because researchers wanted to focus on whether breast-healthy recommendations regarding diet, exercise, and alcohol consumption could plausibly influence disease rates.
Women with relatives who were diagnosed prior to age 45 might have a more dominant genetic pattern so they were excluded.
The data divided women into two groups, those who had a family history of later-onset breast cancer (after age 45) and those who did not. Researchers further categorized the data, based on the degree to which women said they adhered to guidelines for maintaining a healthy lifestyle.
“Complete adherence” equaled a minimum of 20 minutes of vigorous exercise at least five days a week, a normal weight, and drinking no more than one alcoholic beverage a day.
Finally, researchers looked at the cases of invasive breast cancer that arose during a mean follow-up period of 5.4 years. They assessed the relationship between rates of new invasive breast cancer cases, a family history of late-onset breast cancer, and whether either group was modified by the healthy lifestyle recommendations.
Among women with a family history who adhered to all three healthy behaviors, the rate of invasive breast cancer was 5.94 per 1,000 woman-years, compared with 6.97 per 1,000 woman-years among women who adhered to none of the behaviors.
Among women without a family history who adhered to all three healthy behaviors, the rate of invasive breast cancer was 3.51 per 1,000 woman-years compared to 4.67 per 1,000 woman-years for those who adhered to none.
The amount of risk reduced by adhering to the three health behaviors was the same for women with and without a family history.
Breast cancer is the most common form of cancer diagnosed in women, aside from non-melanoma skin cancer. About 15 percent of all postmenopausal women have a genetic predisposition to the disease.
Given the strong awareness of breast cancer and distress about inheritable risk, Gramling says, it is essential that scientists understand the actions women can take to reduce their risk.
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