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 exer