The link between cancer and exercise that patients should know

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We all know that regular exercise has many benefits, including reducing the risk of chronic diseases such as diabetes and heart disease.
Exercise also improves outcomes in patients with cancer, according to a new study published in the New England Journal of Medicine. Patients with cancer who participated in a structured exercise program in a randomized-controlled trial lived longer without cancer recurrence and had a lower risk of dying within the trial period compared with people in the control group.
I was curious why and how exercise reduces cancer risk, and what everyone should know about incorporating exercise programs in their lives. To find out, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore's health commissioner.
CNN: Why are the results of this study so important?
Dr. Leana Wen: Previous research suggested that exercise could be beneficial for cancer survivors, but this is the first randomized trial that demonstrates exercise after cancer treatment can reduce recurrence and improve survival.
Researchers recruited nearly 900 patients from 55 cancer centers across six countries who had been treated for either stage III or high-risk stage II colon cancer. Even after cancer treatments such as surgery followed by chemotherapy, colon cancer comes back in an estimated 30% of patients, according to the American Society of Clinical Oncology. Many patients with recurrence of their colon cancer end up dying from their disease.
The patients in the new study were randomized to two groups. The control group received standard health education materials promoting healthy eating and physical activity. This is the current standard-of-care that is provided to patients in remission from their cancer.
The other group participated in a structured exercise program that involved working with a health coach for physical activity guidance and supervised exercise sessions. During the initial six months, patients had twice-a-month coaching sessions. After that period, they met with coaches once a month, with extra sessions available if needed.
Participants randomized to the structured exercise group had significantly higher improvements in physical function as measured by distance they could walk in six minutes and predicted VO2 max (your oxygen uptake), both indicators of cardiovascular fitness.
The two groups were followed for an average of about eight years. During this period, 131 patients in the control group had recurrence of their cancer, compared with 93 in the structured exercise group. In the control group, 66 people died, compared with 41 in the structured exercise group.
People in the structured exercise group had a 28% lower risk of developing recurrent or new cancers compared with those who followed standard-of-care protocols. Members of the exercise group also had a 37% lower risk of death in the trial period.
This study is important because its rigorous methodology confirms what previous research had suggested: Exercise extends disease-free survival for patients with cancer and should be incorporated as part of holistic treatment for patients to reduce their risk of recurrent and new cancers.
CNN: How might results of the study change treatment for patients with cancer?
Wen: Imagine if there were a clinical trial for a new drug that found it lowered the risk of developing recurrent or new cancers by 28% and lowered the risk of death in the trial period by 37%. Patients and doctors would hail this as a tremendous development and would be eager to try this new therapeutic.
That's the magnitude of the findings in this study. I believe they have the potential to substantially change cancer treatment protocols. Currently, after patients receive treatments such as surgery, chemotherapy and radiation, they are given advice to exercise, but many probably do not engage the services of a health coach or trainer. Their oncologists and primary care doctors may not be asking about their physical activity regimen during follow-up care.
I hope this will change, in view of these results. Patients can be counseled to have an 'exercise prescription,' and health care providers can follow up to track their exercise activity. Perhaps insurance companies could even consider reimbursement for a health coach for patients with cancer; this could be seen as an investment to reduce the need for costlier chemotherapy and other treatments down the line.
CNN: Why and how does exercise reduce cancer risk?
Wen: Population studies have long shown that regular physical activity is associated with lower risks of developing certain cancers. There are several theories as to why this is the case. One is that physical activity helps people stay at a healthy weight, which is notable because obesity is a risk factor for developing some cancers. In addition, exercise is thought to help regulate some hormones that are implicated in cancer development and to reduce inflammatory response that could also be involved in cancer.
CNN: How much exercise do people need?
Wen: The US Centers for Disease Control and Prevention recommends that adults participate in at least 150 minutes of moderate to high-intensity exercise per week. For someone who is exercising five times a week, that's about 30 minutes at a time of exercises such as a brisk walk or jog, riding a bike or swimming.
The benefits of these exercise minutes are cumulative, meaning that individuals don't need to do them all at once to have an effect. People who are unable to commit a period of time to exercise could consider how they could incorporate physical activity into their daily routines. Could they take the stairs instead of the elevator at work? If they do this five times a day, that could be as many as 10 minutes of exercise. Could they take a 10-minute phone meeting while walking in their neighborhood instead of sitting at a desk? Could they park a bit farther away to get in a few more minutes of physical activity? Small changes add up.
CNN: What other advice do you have for people who want to begin exercise programs?
Wen: Many studies show that while it's ideal to get the recommended 150 minutes a week of exercise, there is a significant benefit from even a small amount of physical activity. The best advice I can offer is to not let the perfect be the enemy of the good — start with what you can.
For instance, consider the idea of 'exercise snacks,' or bursts of activity that could be as short in duration as 15 or 30 seconds. These are as simple as doing a few squats or performing household chores. Getting up from your chair and just moving around helps, which is especially important for desk-bound workers who need additional exercise to counter the negative health impacts of sitting.
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