Women age 50 or older who were able to lose weight and keep it off over a 10-year period had a lower risk of breast cancer than women who maintained a stable weight, a new study showed.
In fact, those women who were able to lose the greatest amount of weight were able to lower risk for breast cancer by as much as one-quarter, reported Lauren R. Teras, PhD, of the American Cancer Society in Atlanta, and colleagues.
For the team's study online in the Journal of the National Cancer Institute, weight change and breast cancer risk were assessed in 180,885 women age 50 or older, in data taken from 10 cohorts in the Pooling Project of Prospective Studies of Diet and Cancer. Weight was determined at three timepoints: baseline, approximately 5 years later, and then about 4 years after that.
The results showed that the larger the amount of weight loss, the lower the risk of breast cancer, the researchers reported.
Compared with women in the study with stable weight, women who lost the following amounts of weight had lower risks of breast cancer:
"This message is particularly important for the two-thirds of the U.S. population who are overweight/obese, and therefore at higher risk for breast cancer," Teras and colleagues wrote.
Modifiable Risk
Women who were able to lose more than 20 lbs and gained some, but not all, of the weight back were still at a lower risk for breast cancer, the researchers noted. Additionally, among women who gained up to almost 30 lbs during the first study interval, but subsequently lost all the gained weight, results "suggested a slightly lower risk of breast cancer also, but the CI included the null value," the investigators wrote.
This finding, in particular, suggests that "it is not too late to lower your risk of breast cancer if you have gained weight after age 50," the team added.
According to Sarah P. Cate, MD, of Mount Sinai in New York City, who was not involved with the study, it is not often publicized or discussed with patients that weight and breast cancer risk are connected, making the results of this study important.
"Most of the data we have on breast cancer patients and weight loss is related to risk of recurrence," Cate told MedPage Today. "There is not a lot of data showing that losing weight and sustaining weight loss reduces risk for breast cancer."
These data, therefore, are something clinicians can employ in the clinic in discussions with patients, especially those women who come in and are already at elevated risk, Cate said.
"I sometimes have patients say, 'I can't control my family history, what can I control?' This [study] means that weight is a modifiable risk factor, but it is important to share that it is not just losing the weight, but keeping it off."
Teras and colleagues also pointed out that the results were specific to women who were not using postmenopausal hormone therapy. Among this group, a sustained weight loss of 20 lbs or more resulted in a 32% lower risk for breast cancer compared with those of stable weight.
"Because we know that hormones increase the risk of breast cancer, it was important to show that this bias factor was eliminated," Cate explained.
Teras and colleagues pointed out several limitations of the study including the use of self-reported weight in eight of the 10 cohorts, the possibility of unknown confounders or survival factors, use of data from the 1980s and 1990s when overweight/obesity was lower, and a lack of racial and socioeconomic diversity in the cohorts.
Despite these limitations, "this study addressed the major limitations of previous studies -- specifically, to prospectively examine sustained weight loss during middle-to-later adulthood with adequate sample size in a general population study," the researchers stated.
Teras and co-authors reported having no conflicts of interest to report.
Cate reported no conflicts of interest.
2019-12-17T14:30:00-0500
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