Aerobic exercise and cancer is subject of promising new Duke University study.
When it comes to exercise and cancer, exercise does a lot more than you think.
Not only does it help with our general fitness and keep our waistlines trim and prevent diabetes and heart disease—all important to extending our lives and leading a qualify life as we age. But what we’re learning is the importance of exercise in treating cancer and warding off the disease as well.
A new study from the Duke University School of Medicine published this month in the Journal of The National Cancer Institute shows that aerobic exercise slows tumor growth. The models done by studying mice plays out in both prostate and breast cancer and Mark Wesley Dewhirst, a professor of radiation oncology and co-author of the study, says it’s like to have a similar impact on other cancers once they’re studied.
Dewhirst says doctors and researchers have known since the 1950s that cancer tumors don’t have enough oxygen—a problem that causes radiation and drug resistance and thus hurts in the treatment of cancers.
“It’s been a tough nut to crack that we’ve been trying to figure out,” Dewhirst says.
There are two problems related to the lack of oxygen in cancer, Dewhirst says. One is poor blood flow because vessels formed in the cancer are abnormal and don’t efficiently deliver oxygen, nutrients or drugs to the cancer. Secondly, the cells in the cancer are consuming oxygen because they’re not getting enough and consume it in a fashion that’s not equal to how much is delivered, Dewhirst says.
“We tried lots of things to attack both of those problems and nothing we have tried has worked until we did exercise,” Dewhirst says. “Exercise affects both of those things. It reduces the oxygen consumption rate and kills tumor cells by itself. Secondly. It improves the blood flow by creating a more normal vascular in the tumor than what you normally would get. That’s a perfect solution to the problem. We have solved both of them with one intervention that’s good for you.”
The solution is aerobic exercise rather than other forms of exercise, says Dewhirst who cites an exercise expert who contributed to the study. Weight-bearing exercise doesn’t serve as a substitute because it’s about increasing the blood flow in all parts of the body derived from aerobic exercise, he says.
“The tumors are sitting there so the blood flow in the tumor could also go up as a result of that,” Dewhirst says. “You don’t get that effect when you do weight-bearing exercises. People have asked me if yoga would do it, and I don’t think so because yoga doesn’t get your heart rate up enough. It’s more relaxing.”
The impact of blood flow is why Dewhirst says he believes it will work with other cancers as well.
The study compared exercise to the standard chemotherapy drugs in breast cancer and showed that exercise works as well as that drug in slowing down tumor growth, Dewhirst says.
“It’s a mouse model. I want to make the point in this model and a couple of other models we have looked it slows tumor growth. If you add chemotherapy, the two are better than by themselves,” Dewhirst says. ”I’m not saying you should exercise instead of chemotherapy but exercise will help the efficacy of chemotherapy. It’s healthy. It makes you feel good and it’s going to make the therapy better.”
The best aerobic exercises are the treadmill, stationary or regular bike, running and walking, Dewhirst says. The American Cancer Society guidelines recommend either 75 minutes of intense exercise a week or 180 minutes of moderate exercise, he says.
Epidemiology data already suggests that people who exercise regularly have a lower incidence of cancer and if they do develop it, it occurs later in life, Dewhirst says.
“It tells you that you should be doing it,” Dewhirst says. “What’s important even if you’ve been diagnosed with cancer, it’s been shown that patients who exercise fare better (in other ways). This has been shown in breast cancer. The chemotherapy can be exhausting and if they can push past that, they tolerate chemo much better. I think my takeaway, it’s pretty cheap to go out and exercise.”