Exercise oncology is an emerging branch of medicine that studies the application of exercise medicine in the treatment of cancer. Although there is a strong base of epidemiological research that supports a relationship between increased physical activity and decreased cancer severity and death, the molecular mechanisms that underlie this relationship require further research. Findings of a recent report identify myokines that suppress tumor growth in patients with prostate cancer.
Myokines are molecules released from muscle cells that signal to non-muscle tissues that the body is physically active. Studies in non-human animals have shown that myokines such as oncostatin M, decorin,, and interleukin (IL)-6 suppress cancer growth; however research in humans is lacking.
The investigators recruited 10 men (average age, 73 years) with prostate cancer who were undertaking androgen deprivation therapy, which includes drugs that block the action of testosterone and other male hormones. Participants completed 12 weeks of exercise training that included three sessions-per-week of supervised resistance training and daily self-directed moderate-to-vigorous physical activity. The investigators measured the participants' muscle strength, body composition, and serum myokine concentration before and after the exercise training intervention. They also grew prostate cancer cells in vitro, exposed them to serum from participants taken before and after exercise training, and observed the effects on cancer cells directly.
Participants lost about six pounds of fat and eight pounds of total body weight during the intervention period. Participants significantly increased their strength, measured during the leg press (57 pound increase) and chest press (16 pound increase). Serum concentrations of oncostatin M increased by 82 percent while other myokines did not increase or could not be measured. Finally, prostate cancer cells incubated with serum taken post-exercise training reduced cancer growth by 22 percent compared to serum taken prior to exercise training.
These results show that exercise induced the expression of myokines with tumor-suppressing ability in patients with prostate cancer. Future research is needed to refine the prescription of intensity, frequency, and type of exercise in cancer treatment.
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