- New research finds exercise—specifically two types—causes the release of elements that may prevent cancer cell growth.
- Even one exercise session made a difference.
- Doctors say more research is needed, but here’s what the study found.
Having any type of cancer can be a scary experience, even after you complete treatment. But what if there was a way to attack cancer cells just by exercising? New research looks into just that for breast cancer, specifically, and found that high-intensity interval training and resistance training workouts may play a role in stopping cancer cells from returning.
The small study, which was published in the journal Breast Cancer Research and Treatment, analyzed health data from 32 breast cancer survivors. The patients were assigned to do a single session of resistance training or high-intensity interval training (HIIT), and the researchers collected blood before the patients’ workouts, immediately after, and 30 minutes after that. The researchers looked for specific markers of tumor-suppressing elements in the patients’ blood, including decorin, interleukin 6, secreted protein acidic and rich in cysteine (SPARC), and oncostatin M (OSM), along with the growth of MDA-MB-231, a breast cancer cell line.
Meet the experts: Rob Newton, Ph.D., study co-author and professor of exercise medicine at Edith Cowan University; Jack Jacoub, M.D., medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA; Janie Grumley, M.D., breast surgical oncologist and director of the Margie Petersen Breast Center at Providence Saint John’s Center in Santa Monica, CA
The researchers discovered that levels of the cancer-suppressing factors “significantly increased” after both HIIT and resistance training workouts, while cancer cell growth was “significantly reduced.” HIIT workouts had the biggest effect on MDA-MB-231 cell growth reduction.
The findings suggest that exercise is “potentially contributing to a lower risk of recurrence,” the researchers wrote in the study’s conclusion. “This highlights the importance of exercise as a treatment with promising anti-cancer effects,” they added.
Why might HIIT and resistance training workouts suppress cancer cell growth?
This isn’t the only study to link exercise with better cancer outcomes. Research suggests that exercise may reduce the risk of cancer recurrence and mortality by up to 28%. Another study found that people who were able to stay physically active after a cancer diagnosis had an up to 23% lower risk of dying compared to their less-active peers.
But…why? “When we exercise intensely, our muscles release powerful signaling molecules called myokines into the blood,” explains Rob Newton, Ph.D., study co-author and professor of exercise medicine at Edith Cowan University. “These act as endogenous medicines: Some of them can directly slow down cancer cell growth in the lab, and that’s exactly what we observed after a single bout of resistance or HIIT exercise.”
But it’s hard to say for sure that exercising will help suppress cancer growth, says Janie Grumley, M.D., breast surgical oncologist and director of the Margie Petersen Breast Center at Providence Saint John’s Center in Santa Monica, CA. “This is measuring some very specific markers. We don’t know that there’s a direct link to decreasing cancer—they’re assuming these markers are important,” she says.
The study also followed a small group of patients, which makes it hard to say for sure that exercising will reduce the risk of cancer recurrence, says Jack Jacoub, M.D., medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA. “But it adds to the evidence that exercise is an important part of good health,” he says. “If you’ve had cancer, whether it’s breast cancer or, I suspect, any cancer, it behooves you to exercise because there’s a good chance that it contributes to preventing recurrence.”
Newton acknowledges that “cells in a dish are not the same as the human body,” but he stresses that the study helps to explain why exercise may have a beneficial impact on cancer recurrence.
What does this mean for people without a history of cancer?
While experts say that more research is needed, they also say the findings suggest that exercise may help lower your risk of developing cancer in the first place.
“The same molecules are released whenever we exercise, whether or not we have cancer,” Newton says. “That may help explain why active people are at lower risk of developing cancer in the first place.”
Dr. Grumley agrees. “There probably is potentially something here, but we don’t know exactly what that is,” she says.
What should people take away from this?
Dr. Jacoub points out that there’s no harm—and plenty of benefit—from having a regular exercise routine, if you’re able. Working out regularly is also linked to other healthy, cancer-reducing benefits, he says. “Everything is intertwined to some degree,” he says. “You’re probably limiting drinking [alcohol], eating well, and not smoking like a chimney if you’re exercising regularly. All of those things tend to go hand-in-hand.”
Dr. Grumley says she counsels her patients on the American Cancer Society’s recommendation of doing heart rate-elevating exercise for 150 minutes a week. “That’s heart rate-elevating; Not just going for a walk,” she says. Dr. Grumley also stresses the importance of making exercise part of a healthy lifestyle, “not just I have to do this exercise routine once or for this many weeks and I’m good.”
But Dr. Grumley also stresses that cancer recurrence is complicated, and there are still a lot of unanswered questions about why exercise may lower the risk of the disease coming back. “We don’t want to guilt patients into thinking that they caused their cancer by not working out,” she says.
Overall, Newton says taking up an exercise habit is a good idea, whether you have a personal history of cancer or not. “Exercise isn’t just safe during and after cancer—it may actively fight the disease,” he says. “Even one session produced blood changes that slowed cancer cell growth. This makes exercise a powerful, accessible treatment that should be part of cancer care alongside standard treatments.”