Dec. 10, 2021 -- Nancy Howe’s oncologist was emphatic: You need to take it easy. It was 1997, and Howe had just had surgery for head and neck cancer. Now she had to withstand 7 weeks of radiation therapy, and the side effects that go with it -- deep fatigue most of all.
Howe had always been physically active but had lost muscle and felt depressed whenever she couldn’t exercise due to injuries.
“I knew I’d be better off if I stayed as active as I could,” says Howe, of Phoenix, AZ.
Howe defied her doctor’s orders to rest during cancer treatment, the usual advice in the late 1990s. She kept going to the gym, even if some days, all she could manage was a few minutes on an exercise bike, and she walked around her neighborhood. Her keep-it-moving instinct paid off.
“I came through the treatment much better than anyone expected,” says Howe, now 65. “I had more energy and I didn’t lose a lot of muscle, which made it easier for me to recover after radiation.”
Unknown to her, Howe had embraced an idea that continues to gain acceptance in medicine today: Exercise is a potent weapon against cancer.
Research in the fast-growing field of exercise oncology has left little doubt that staying physically active improves symptoms and side effects during cancer treatment. And there’s now solid evidence that exercise reduces the risk for some cancers and lowers the odds of dying if you are diagnosed with certain forms of the disease.
Still, in the minds of many, including some oncologists, exercise and cancer do not go together, says Kathryn Schmitz, PhD, director of the Oncology, Nutrition, and Exercise Group at the Penn State Cancer Institute.
“If you ask the average person on the street whether your Aunt Betty who has cancer should she be exercising, they’ll say, ‘Heck, no, she should be sitting with a blanket over her knees,’” says Schmitz, author of Moving Through Cancer and an evangelist for exercise oncology. Cardiologists used to order heart attack survivors to rest, she says, “but now we get them out of bed the next day and we have them in cardiac rehab within a week.”
Attitudes about exercise in oncology are changing, she says, but still have a lot of catching up to do.
Forty Years of Exercise Oncology
Exercise oncology’s origins are usually traced to the 1980s, when a series of studies at Ohio State University found that breast cancer patients having chemotherapy who exercised regularly -- a radical idea back then -- had less fatigue, nausea, and disability from the treatments.
That groundbreaking work helped trigger a tsunami of research on the link between exercise and cancer. In 2019, Schmitz co-chaired an international panel of experts that reviewed the science and found that exercising during and after treatment for cancer eases fatigue, anxiety, and depression, while improving quality of life and physical function. That is, the ability to go about a normal day.
Meanwhile, prevention is also part of the equation. Studies strongly suggest that exercise lowers the risk for seven forms of cancer: bladder, breast, colon, endometrial, esophageal, kidney, and stomach.
There are also intriguing clues that exercise helps prevent lung, blood, head and neck, ovarian, pancreatic, and prostate cancers, too. And exercising appears to reduce the risk of dying in people diagnosed with breast, colorectal, and prostate cancers, in the range of 40% to 50%. Those kinds of numbers and that amount of research are hard to ignore.
Just how might huffing and puffing fight cancer? No one is sure, but Schmitz points out that exercise reduces levels of inflammation and insulin, which are linked to some cancers.
Also, exercise induces angiogenesis, or the creation of new blood vessel, she notes, which could mean that more blood-driven anti-cancer medicine can be delivered to malignant tumors.
“Exercise may actually change the potency of chemotherapy,” says Schmitz.
Why It Helps
Immune function also plays a role. While cancer weakens the immune system, a single bout of exercise produces a flood of defender immune cells, says Michael Gustafson, PhD, scientific director of the Nyberg Human Cellular Therapy Laboratory at the Mayo Clinic’s Arizona campus.
Gustafson and colleagues found that pedaling full-speed on a stationary bike for 10 minutes can boost tumor fighters called natural killer cells by 10 times; protective T and B cells rise in the blood, too.
“I don’t believe that exercise alone can cure you of cancer, but I do believe that it can be very helpful,” he says.
By using exercise to help cancer patients build up bigger armies of defender cells, Gustafson believes it may be possible to make powerful immunotherapy treatments work better. Those treatments “teach” a patient’s own immune cells to attack tumors.
It’s also well-known that body fat makes the hormone estrogen, which can cause some forms of breast cancer, says Betsy O’Donnell, MD, director of the Lifestyle Medicine Clinic at Massachusetts General Hospital in Boston.
Exercise, along with cutting calories, helps reduce body fat, a concern for many breast cancer patients, who often gain weight during treatment.
“Weight gain can have major implications for self-esteem and quality of life, too,” says O’Donnell.
At her clinic, patients work with a nutritionist, behavioral psychologist, and other specialists, in addition to getting help with improving their physical fitness.
Research shows that aerobic exercise (such as walking, jogging, or cycling) and strength training (such as lifting weights or using resistance bands) can benefit cancer patients.
An oft-cited 2007 study published in the Journal of Clinical Oncology involving 242 women with breast cancer who were about to begin chemotherapy found that aerobic exercise improved patients’ self-esteem and reduced body fat, while resistance training helped build muscle and made them more likely to finish their treatment.
Need for Personal Programs
Not all cancer survivors are eager to hit the gym during or soon after the rigors of treatment, so tailoring the intensity of an exercise prescription to each patient is essential, says O’Donnell.
Walking is perhaps the most popular option many of her patients choose, particularly since many people have been avoiding gyms due to the COVID-19 pandemic. She recommends building up to at least 150 minutes of walking per week, maintaining a pace that allows you to talk, but not sing.
And if walking isn’t for you, O’Donnell says, some of her patients instead dance, learn tai chi, or find some other form of purposeful movement that they enjoy.
“You really need to meet patients where they are, both in terms of their physical abilities and their desire to participate,” says O’Donnell. (You can find exercise videos for a variety of fitness levels developed by her clinic here.)
Nancy Howe was so convinced that staying active helped her cope with cancer treatment that she quit her job as a software engineer and became a fitness trainer for cancer patients and survivors. A doctoral candidate in nursing and health innovation at Arizona State University, her thesis project involves adapting a tool doctors use to choose the right level of exercise for cancer patients so it can be used by the patients themselves.
But, in the end, the advice for patients is simple.
“It’s really important to do something now, wherever you are in your cancer journey,” says Howe. “Just start.”