In a groundbreaking study that made headlines around the world, researchers working with the Sinclair Cancer Research Institute and Kingston Health Sciences Centre demonstrated that a three-year program of structured exercise significantly improves survival for patients with colon cancer by reducing the risk of disease recurrence and new primary cancers. The study was led by the Canadian Cancer Trials Group at Queen’s and funded by the Canadian Cancer Society. We asked Dr. Christopher Booth, co-chair of the CHALLENGE trial and a professor in the Departments of Oncology and Public Health Sciences, what this means for patients, the health-care system, and the future of cancer research.
This research resulted in a global first. Can you explain what makes it so groundbreaking?
This is the first clinical trial in the world designed specifically to ask whether exercise can improve cancer survival. As oncologists, one of the most common questions we get asked by our patients when they finish chemotherapy is, “Doc, what else can I do to improve my outcomes?” We now have strong evidence that a structured exercise program delivered after surgery and chemotherapy for colon cancer improves survival. This finding has changed standard care overnight and has generated tremendous interest in studying the effects of exercise in other cancers.
This study received tremendous media attention. In one interview, you said researchers were “astounded when we saw the magnitude of benefit of exercise.” Explain a bit about why everyone was taken aback by the findings – the coverage suggests this is really a seismic shift in what we know about cancer.
We launched this study in 2009 based on early data from other studies suggesting a potential association between exercise and cancer outcomes. However, until now, we did not have proof that exercise can improve survival. What was so astounding was the magnitude of benefit. For every 14 patients who went on the exercise program, exercise prevented one person from dying. This magnitude of effect is comparable (and in some cases exceeds) the benefits of many of our standard chemotherapy treatments. The CHALLENGE trial has clearly demonstrated that surgery, chemotherapy, and an exercise program are together the new standard treatment for patients with Stage 2 and 3 colon cancer.
The study does not reveal exactly how exercise reduces the new onset or recurrence of cancer. What are some of the theories about why exercise had such a powerful impact?
Prior laboratory studies have suggested a number of different anti-cancer effects of exercise. Exercise has known beneficial effects on the immune system, inflammation, metabolic health, and cardiovascular circulation. It is plausible that several factors are driving the results we saw in the CHALLENGE trial. We collected blood specimens on all 889 patients who participated in this global trial at multiple points during the three-year study period. In the next one to two years, we will be doing detailed analyses of these specimens to try to better understand the effects of exercise on cancer.
For patients currently going through cancer treatment or recovery, what kind of exercise are we talking about? In the study, patients could decide what kind of exercise they wanted to do – was any one kind of exercise better than another? And how intense did exercise have to be?
Our study tested the role of aerobic exercise. Patients had a target level of exercise that could be met using any form of cardiovascular physical activity. A physical activity consultant worked with patients every two weeks for Year 1 and then monthly during Years 2 and 3. They played a crucial role as a motivational coach and designed an “exercise prescription” that would allow the patient to hit their physical activity target doing activities they enjoyed. This included everything from swimming to cross-country skiing to biking to kayaking and jogging. Most people, however, started a walking program and could hit their target if they walked at a brisk pace for 45-60 minutes three to four times per week.
Many people think of cancer recovery as a time to rest. How can patients know when it’s safe to start exercising?
An exercise program is likely a good idea for everyone. However, for someone being treated for cancer, this needs to be done in conjunction with the treating oncologist. The amount of exercise that is appropriate will vary based on how sick the patient is and what other forms of treatment they are receiving. The patients in our study had completed surgery and chemotherapy and recovered from the treatment side effects before they started this program. Patients should speak with their oncologist before they start a new exercise program.
One of the key components of the study was a physiotherapist or a personal trainer for the patients to check in with on a regular basis. How did those factors make a difference?
My patients who participated in this study were emphatic that it was the human connection with their trainer that made a huge difference in their ability to start and maintain an exercise program. Patients felt accountable to their trainer and highly motivated to work on the goals they designed together.
The New York Times noted that, after eight years, the exercise program had prevented one death for every 14 people who participated in the exercise arm of the study. So many people have been touched by cancer – can this give us all hope that we can improve cancer survival rates in the future, or are we getting ahead of ourselves?
This is the first study to demonstrate that exercise can improve cancer survival, and it is specific to colon cancer. Our data provided a hint that exercise can also prevent new cases of breast cancer and prostate cancer, but more work is needed to better understand this. In fact, there are ongoing trials in breast cancer and ovarian cancer exploring the extent to which diet, nutrition, and exercise can improve survival.
For people who want to act now – whether they’ve had cancer or not – what advice would you give about exercise and cancer prevention?
Exercise is good for the mental health, emotional well-being, and physical health of all of us. For patients currently being treated for cancer – it will be important for them to speak with their oncologist about what program might be appropriate for them.
