Research shows that physical activity offers plenty of benefits for long-term health and plays an important role in both cancer prevention and healthy survivorship. For reducing cancer risk, American Institute for Cancer Research (AICR) recommends getting at least 150 minutes of moderate, or 75 minutes of vigorous (if possible) physical activity per week. Emerging evidence shows that physical activity, can be a valuable complement to traditional cancer treatments as well. A recently published paper supports the role of physical activity in increasing the effectiveness of radiation therapy, chemotherapy and even immunotherapy.
“Exercise could be evaluated as a means to improve treatment response to established cancer treatment modalities,” says lead author Kathleen Ashcraft, PhD, from the Duke University School of Medicine. It can alter the tumor microenvironment, or the mixture of blood vessels, cells and molecules that surround a tumor, to create conditions more antagonistic to growth or even more supportive of antitumor treatments.
The region surrounding tumors is typically hypoxic, or low in oxygen, because blood vessels are not able to deliver enough oxygen amidst the “chaotic and immature vessel structure.” Hypoxia causes damaging oxidative stress to the body’s tissues and that stress is further aggravated by treatment.
This paper cites studies in mice that observed improved efficacy of chemotherapy in reducing tumor growth after running. The authors suggest, this is caused by increased access to tumor cells, improved consistency of blood flow and improved drug delivery via reduced pressure of surrounding fluid. Exercise—even a single bout of running—can increase blood flow to a tumor site and decrease vascular resistance, thereby improving access by drugs.
The authors also suggest that exercise causes T cells (an important subtype of white blood cells that play a key role in fighting cancer) to redistribute to peripheral tissues following exercise, which enhances the immune system’s ability to access tumor cells. Immunotherapy, which enhances the body’s own immune system, may also be better able to target tumors following exercise by enhancing oxygen delivery.
Radiation also has a harder time killing hypoxic cells, so exercise can help with the treatment by increasing oxygen levels. The authors suggest exercise may help to reprogram cancer cells’ metabolism in a way that reduces oxygen consumption to help prevent hypoxia. Other benefits may include reduced acidity and increased efficacy of chemotherapy when normal cancer cell metabolism is inhibited.
The authors maintain that although additional work is needed to optimize exercise prescriptions (i.e., frequency, duration, and intensity), current studies suggest that human trials should be considered. Meanwhile, their conclusions point toward many possible ways cancer patients can benefit from engaging in regular exercise. Even if they struggled to exercise regularly prior to treatment, it may very well not be too late to start. Integrating both aerobic activity, that raises heart rate and promotes cardiovascular endurance, as well as strength-training, can help to have these effects. Walking a few times per week and using small hand weights—or even three-pound objects lying around the house—are a great place to start. These strategies can easily fit into AICR’s recommendations for physical activity per week.