Gaining weight after age 20, even just a pound or two per year, can nearly double the risk of developing breast cancer after menopause compared to women who keep their weight stable. This finding, from a National Cancer Institute (NCI) study, reported on the equivalent of a 30-pound gain over the years for a five-foot, four-inch woman. This extra weight acted as a major risk factor for breast cancer, and was as significant as family history of the disease, the age at which a woman begins to menstruate (the earlier, the higher the risk), or whether or not she has had children and the age at which she gave birth, according to study co-author Regina Ziegler, Ph.D., an NCI epidemiologist. The NCI research team, working with investigators from Columbia University's Mailman School of Public Health, analyzed information from 72,007 postmenopausal women in NCI's Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) cohort to arrive at the conclusions. Bear in mind that doubling the risk of any disease, while not desirable, isn’t as awful as it sounds. For example, if the normal risk were one in 100, double the risk would be two in 100.
My take? We've long known that being overweight or obese increases the risk of breast cancer. This study is newsworthy in that it helps quantify the added risk. There's nothing women can do about the most common risks of breast cancer: being female and getting older, but weight is something you can strive to control through healthy eating and regular exercise. Breastfeeding your babies, avoiding alcohol and long term estrogen replacement therapy at menopause, eating less meat and avoiding exposure to environmental pollutants can also help reduce your breast cancer risk, as can taking two grams of fish oil per day for the omega-3 fatty acids it provides.
Learn more about breast cancer.