Credit: Aaron Logan
Exercising during doxorubicin treatment can amplify the drug’s cancer-fighting ability, according to preclinical research.
Previous studies showed that adopting an exercise regimen before receiving doxorubicin could protect against the cardiac side effects associated with the drug.
Now, researchers have reported that exercising during doxorubicin treatment does not protect the heart, but it does help shrink tumors in mice.
Joseph Libonati, PhD, of the University of Pennsylvania in Philadelphia, and his colleagues reported these findings in the American Journal of Physiology—Regulatory, Integrative and Comparative Physiology.
The researchers conducted experiments with 4 groups of mice, all of which received an injection of melanoma cells.
During the next 2 weeks, 2 of the groups received doxorubicin in 2 doses, while the other 2 groups received placebo injections.
A treated group and a placebo group were put on exercise regimens, walking for 45 minutes 5 days a week on mouse-sized treadmills, while the rest of the mice remained sedentary.
After the 2-week trial, the researchers examined the animals’ hearts using echocardiogram and tissue analysis.
As expected, doxorubicin reduced the heart’s function and size and increased fibrosis. Mice that exercised were not protected from this damage.
“We looked, and the exercise didn’t do anything to the heart; it didn’t worsen it, it didn’t help it,” Dr Libonati said. “But the tumor data—I find them actually amazing.”
The mice that received doxorubicin and exercised had significantly smaller tumors after 2 weeks than mice that only received doxorubicin (P<0.05).
Further studies will investigate exactly how exercise enhances the effect of doxorubicin, but the researchers believe it could be, in part, because exercise increases blood flow to the tumor, bringing with it more of the drug in the bloodstream.
“If exercise helps in this way, you could potentially use a smaller dose of the drug and get fewer side effects,” Dr Libonati said.
Gaining a clearer understanding of the many ways that exercise affects various systems of the body could also pave the way for developing drugs that mimic the effects of exercise.
“People don’t take a drug and then sit down all day,” Dr Libonati said. “Something as simple as moving affects how drugs are metabolized. We’re only just beginning to understand the complexities.”
