Here we go again. Physical activity is linked to hormone-negative breast cancer. Oh, wait, it isn't. A new study that links sitting too long to an increased risk of breast cancer is getting a lot of media play lately. Its results, though, are limited to hormone-positive disease—a detail most reports ignore because, in general, most media reports ignore the significant difference between hormone-receptor-negative breast cancer and hormone-receptor-positive breast cancer.
Roxanne Nelson of Medscape Today, however, gets it right. In her overview of the "sitting too long" study, which was reported at the Tenth Annual American Association for Cancer Research (AACR) Conference on Frontiers in Cancer Prevention Research, Nelson writes:
The researchers found a significant protection of physical activity only for the estrogen-receptor (ER)-positive and progesterone-receptor (PR)-positive tumor types, said Dr. Steindorf. "These findings strengthen the hypothesis that lowering breast cancer risk with physical activity is at least partly related to hormonal pathways."
That is, researchers did not find a significant link between hormone-receptor-negative breast cancers such as triple-negative and exercise. So, our lack of exercise was less likely a factor in our getting this form of disease. Results also varied by menopausal status, with postmenopausal women gaining more of a benefit from physical activity than premenopausal women. As we know from other research, TNBC is more likely to affect younger, premenopausal women.
BUT, previous research has linked a lack of physical activity to an increased risk of hormone-negative breast cancer. And the effects of a lack of exercise, specifically metabolic syndrome, have been tied to triple-negative breast cancer. Symptoms of metabolic syndrome include obesity, high blood pressure, and high cholesterol. Exercise can trim all three.
I could go on, but the point here is that studies differ in their results for a variety of reasons—especially their methodology and the population they study—so one study is neither cause for alarm nor cause for complacency.
Physical activity, if you can handle it, is a great thing. It helps you in both body and soul. I will continue to get myself out to do at least four hours of decent exercise a week—usually a brisk walk. I always feel better afterwards and I know for a fact I cannot keep my weight at a healthy level without it.