Exercise has some amazing benefits for the human body, so perhaps it’s not surprising to learn that it can also be hugely beneficial for people who are on medications or who are undergoing treatment for cancer. But a recent study may give you two more reasons to smile after your workout: your medications may work better, and you may experience fewer side effects.
These benefits may be due in part to the fact that exercise mobilizes the immune cells and encourages the body’s natural killer cells to kill tumor cells. The benefits of exercise in killing off cancer may also be related to the fact that the blood vessels in a tumor are typically “immature and poorly functional.” Exercise can help improve blood flow and grow new blood vessels, which means chemotherapy drugs are more efficiently spread within a tumor.
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“Only 50 percent [of blood vessels in a tumor] are carrying blood and therefore chemotherapy,” says Dr. Keri Schadler, an assistant professor of pediatrics research at the University of Texas MD Anderson Cancer Center. “Most of the drugs end up being delivered at the periphery of the tumor, which explains why treatment isn’t as effective as it could be.”
A 2019 study published in the journal Scientific Reports measured the number of blood vessels in the pancreatic tumors of mice. Dr. Schadler found that mice who exercised on treadmills for 45 minutes a day five times a week had five times the number of active blood vessels in their tumors as mice that didn’t exercise.
“We treated them until the tumors had disappeared, and the mice that got the combination of exercise and chemotherapy then had slower regrowth of the tumor,” says Dr. Schadler. “This showed that chemotherapy combined with exercise worked better when the tumor was present but also that it seemed there was a delay in regrowth of tumor after the treatment stopped.”
But why does this occur? Dr. Schadler has at least part of the answer:
“The evidence suggests that as you’re exercising and your blood is flowing faster, you’re getting a stronger mechanical signal on the endothelial cells that make your blood vessels, and that is signaling to those cells to behave differently and become more mature functional blood vessels,” she says.
This study was followed up with a study of pancreatic cancer patients who did 60 minutes of aerobic activity and 60 minutes of strength training per week. This study found a “significant change” in the number of blood vessels within the patients’ tumors compared with patients who didn’t exercise, and exercise reduced some of the side effects of chemo as well.
Exercise has also been shown to decrease the risk of certain types of cancers returning after treatment, according to a 2019 study review. Colorectal patients who exercised while undergoing treatment, for example, were 30 percent less likely to die over the next eight to ten years.
Future research will continue to try to discover the other ways in which exercise may impact cancer patients. But for now, it’s enough to know that exercise may actually help you fight cancer and reduce your side effects. So in addition to whatever medications you’re taking these days, don’t forget to also get your dose of the wonder drug that is exercise!