Chemicals released after intense exercise slow breast cancer growth

Exercise has long been linked to better outcomes for women with breast cancer – and a recent study might explain why. According to researchers from Denmark, physical activity that’s intense enough to cause breathlessness creates a chemical release in the body.

This releases compounds called catecholamines and one in particular – epinephrine – helps suppress the growth of tumour cells.

Senior study author, Pernille Hojman, from University of Copenhagen, told Reuters Health: “It is important to highlight that exercise training and epinephrine did not completely prevent tumor formation, but induced a 50 percent reduction.

“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.”

Numerous population studies have shown that regular fitness can reduce a woman’s risk of breast cancer and, in those who already have breast cancer, may keep it from coming back. But 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.