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Exercise Again

Posted 10/22/2015

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  I am aware that exercise is a frequent (? too frequent) topic here, but the information keeps pouring in about how important it can be. You will recall previous posts that have suggested the possibility that regular mild to moderate exercise can reduce the recurrence risk in many cancers and may reduce the risk of getting cancer in the first place. Now this comes from Newsweek, hardly an arcane scientific journal.

 .A New Prescription for Cancer Patients: Exercise
New research shows working out may ease the effects of chemotherapy for some patients.
Until recently, many doctors assumed exercise would be too draining on cancer patients undergoing chemotherapy.

 By Steve Sternberg

New research is chipping away at the doctrine that says cancer patients should take it easy. Until recently, many doctors—and patients—assumed that exercise was too draining and might be unsafe, particularly during the rigors of chemotherapy, with its challenging side effects and overwhelming fatigue.

But emerging evidence suggests that exercise is safe and may help blunt the devastating impact of chemotherapy on fitness—and, ultimately, speed recovery. Increasingly, scientists are also beginning to look even deeper, to examine the impact of exercise on cancer progression. Lee Jones, an exercise physiologist at Memorial Sloan Kettering Cancer Center, poses the question this way: “What is exercise doing to tumor biology, the ability of these cells to grow and prosper?”

Jones says he long nurtured an interest in biology and sports. As he dived deeper into his discipline, his focus veered from sports medicine to the clinical applications of exercise in health care: What are the normal physiologic responses to exercise? What are they for people with heart disease and cancer?

These interests converged, he says, as cancer survivors began living longer with hearts that had been exposed to prolonged bouts of damaging chemotherapy. And not just their hearts but also their lungs, muscles and blood. “This would have a fundamental effect on fitness,” Jones says.  

Fifteen years ago, he began designing studies to test whether a structured exercise program could stave off the “global deconditioning”—or physiological decline—that results during cancer therapy. “At the time, people thought we were crazy,” he says. “You’re going to exercise patients who have cancer?”

But the findings were striking. In women with breast cancer who didn’t exercise, chemotherapy took a major toll on aerobic fitness, aging them prematurely. “Ten weeks of chemotherapy is equivalent to 10 years of normal aging, Jones says. “It turns a 50-year-old into a 60-year-old; a 60-year-old into a 70-year-old.”  

When cancer patients who exercised were compared with those who didn’t, Jones says, the difference was striking. “Exercise completely prevented the decline that we saw in the control group.”

The findings were impressive, says Donald McDonnell, a professor of pharmacology and cancer biology at Duke University School of Medicine, who worked with Jones at Duke. “Usually, you need a green laser to point out [subtle] differences in the two groups. Not this time.  His results were dramatic.”

There are other intriguing hints that cancer patients who exercise may be better off, Jones says. Some studies of disease patterns in cancer patients, for instance, have shown that people with cancer—breast, prostate and colorectal--who report higher levels of exercise have a fewer recurrences and lower death rates. 

Confronted with this evidence, Jones began to wonder whether exercise could have an impact on tumors themselves. Some tumors, for instance, thrive in low-oxygen environments. Exercise pumps oxygen into tissues, which could discourage their growth. Other studies suggest that exercise may bolster the effectiveness of chemotherapy. 

“I think about exercise as if it’s a drug,” he says. “How much do I need to give? Does it work? Are there some patients who respond better than others?”

The latest data indicates that how well a tumor responds to exercise, and whether it recurs, depends on the characteristics of the tumor. “Right away that tells you it’s not a uniform impact,” Jones says. “With a different tumor, there may be a different exercise prescription.”

What sets Jones’ work apart, says McDonnell, is that before he came along, “a lot of this stuff was not great science. Jones was one of the first to do prospective clinical trials.”

Jones says he’s ramping up to do even more at Memorial Sloan Kettering—14 studies, over the next three to five years, involving 400 to 500 patients. 

“It’s early days,” he says. “If we think of this from the standpoint of the evidence, there are 120 studies looking at the impact of exercise on cancer. There are 3,500 in heart disease.”



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