Brief, intense exercise may keep breast cancer at bay

(Reuters Health) - Exercise has long been linked to better outcomes for women with breast cancer, and a recent study might explain why.

Brief exercise that’s intense enough to get your heart rate elevated and make you breathe heavily activates molecular pathways in the body that boost chemicals called catecholamines, such as epinephrine, which suppressed the growth of breast cancer cells, researchers from Denmark found.

“It is important to highlight that exercise training and epinephrine did not completely prevent tumor formation, but induced a 50 percent reduction,” senior study author Pernille Hojman from University of Copenhagen told Reuters Health. “Thus, exercise training can never replace anti-cancer therapy, but could be an effective supportive strategy, which in addition to the biological effects, also has been shown to increase the patients’ quality of life and sense of empowerment.”

Plenty of population studies have shown that exercise can reduce a woman’s risk of breast cancer and, in women who already have breast cancer, may keep it from coming back. Few studies have examined how this works.

Hojman’s team used experimental mice implanted with human breast cancer tumors as well as tumor cells in test tubes to investigate how serum samples collected from healthy women and breast cancer patients before and after exercise affect the development of the breast tumor cells, and what mechanisms were involved.

They found that serum samples taken after exercise reduced the ability of tumor cells to grow in test tubes or in mice. Only 45 percent of mice with tumors steeped in post-exercise serum developed tumors, compared with 90 percent of mice with tumors not exposed to post-exercise serum or exposed to pre-exercise serum.

The researchers traced this anti-tumor activity to a rise in epinephrine and norepinephrine that occurs with moderately intense exercise and its effect on the a gene-signaling pathway known as Hippo that, among other things, helps to suppress tumor development.

This effect emerged only with serum samples taken after 15 minutes of moderate- to high-intensity exercise, according to the report in Cancer Research, and it was not related to the serum-donor’s body weight, blood sugar levels or immune responses.

“In our study, we found that breast cancer patients in adjuvant chemotherapy, were indeed capable of performing the required exercise, so it is feasible for cancer patients to do the exercise training we are proposing,” Hojman noted in an email interview.

“Our identified mechanism of an epinephrine-driven regulation of the Hippo signaling pathway during exercise could certainly also be envisioned to work in other types of cancer,” she said.

SOURCE: Cancer Research, online September 8, 2017.