When Kerry Courneya arrived at the University of Calgary in 1992, cancer was the farthest thing from his mind. Trained in exercise science, he was networking to find people to collaborate in his field when he was put in touch with Christine Friedenreich from the Alberta Cancer Board. Her main interest was exercise, so the meeting sounded promising.
When they finally met, Dr. Courneya discovered that while Christine was in fact interested in exercise, her focus was on whether exercise could reduce the chance of developing cancer. Subsequent conversations with her led to a discussion of what could be done for people who have already been diagnosed with cancer. At that time, physical activity (PA) was not considered to be an essential component of their treatment plans, so Dr. Courneya began to explore the possibilities of what PA could do to help cancer patients at various stages post-diagnosis, and if it could improve their long-term survival.
Since beginning his research, Dr. Courneya has conducted some of the most influential studies in this area and is a pioneer in developing the field of PA and cancer survivorship, also known as exercise oncology. His vision is to have PA implemented as an essential component of cancer care similar to chemotherapy and radiation therapy.
Could PA work for all cancers?
Recent research suggests that exercise benefits most people both during and after cancer treatment. It can help manage some of the common side effects of treatment, speed up their return to normal activities, and improve their quality of life. The evidence also shows little risk of exercise causing harm if care is taken and professional exercise advice is followed closely and, for certain cancers, exercise may even improve treatment outcomes.
According to Dr. Courneya, there are more than 100 types of cancer but since most research is done in breast, prostate and colorectal, these cancers have the largest volume of data and evidence. In terms of the risk of recurrence and improved survival, exercise seems to be most effective with breast, prostate and colorectal cancers. Exercise is not likely to improve survival rates in all cancer patient groups such as liver or pancreatic cancers but this is partly due to lack of research. However, Dr. Courneya is more hopeful about the positive impact PA could have on a broader range of cancer patients: “I think there’s evidence that it (PA) might cut across these cancer patient groups, even some of the ones we haven’t studied that much,” says Dr. Courneya. “Exercise seems to improve fatigue in all sorts of cancer patients and improve quality of life, fitness and strength.”
Still, the strongest evidence is with colon cancer. What is it about exercise that reduces the risk of developing colon cancer in particular?
There are two major factors that have an effect; the first is mechanical and the second, biological. On the mechanical side, it’s simply the passing of food through the colon.
“People who exercise regularly are also more regular in terms of going to the bathroom so lower rates of constipation and more quickly moving the food through the system,” explains Dr. Courneya. “The food moves through the system in the form of feces or stool and, as it moves, the carcinogens in the feces are not in contact with the colon as long. When people are constipated, the feces stay in the colon longer which means more contact with the carcinogens that it may contain.”
The biological impact of PA is linked to the stimulation of the immune system and the reduction of inflammatory markers. The immune system contains what are known as “natural killer cells”. During exercise, these cells can be stimulated to be more active against lingering cancer cells. PA has also been shown to reduce inflammation and reduce exposure to sex hormones like estrogen and testosterone which also make cancers grow more quickly.
“Many [researchers] are looking at the mechanisms that shrink cancer tumours and inflammation is part of the mechanism,” says Dr. Courneya. “People who exercise might have lower levels of these [inflammatory] markers all the time. Markers may change after bursts of exercise which means it’s better to exercise more regularly. Then you would lower these inflammatory markers every day and lower your risk for cancer. Is the effect acute or chronic? That’s the current debate,” he concluded.
Preparing for treatments
In some cancers, intervention is possible even before treatment begins. In this “pre-habilitation”, work is done on the patient’s fitness and function with the goal of getting them fitter, stronger, and in a better frame of mind emotionally. “Some research has shown that if you are fit and healthy going into these major treatments, especially surgery, that the length of hospital stay afterwards is shorter, there are fewer post-op complications or complications from other treatments, and patients will recover more quickly afterwards,” explained Dr. Courneya.
Helping patients cope
Chemotherapy can last anywhere from four to six months and radiation therapy can add another five to six weeks. That’s a long time to be on treatments that carry some heavy side effects including nausea, diarrhea, peripheral neuropathy, fatigue, and depressive symptoms. Some of Dr. Courneya’s work has demonstrated that patients who exercise during chemotherapy treatments actually complete more of their treatments than patients who don’t exercise. “That means they get all the drugs and they get them when they’re supposed to get them,” says Dr. Courneya. “And that’s really important for cancer patients because if your treatments are reduced at all or they’re delayed, there’s a higher risk of the cancer coming back,” he explained. “Exercise has been shown to help with the treatments in part by managing the side effects so patients don’t have to stop these treatments. So you really want to complete all of your treatments on time if you can.”
Staying active during recovery
Chemotherapy and radiation are extremely taxing on the body. Patients undergoing these treatments are often extremely ill and, understandably, in no mood to exercise. However, this isn’t to say that they can’t exercise. In fact, Dr. Courneya asserts that despite how hard these treatments are, most cancer patients actually can exercise during treatment and it’s really important for recovery after treatment. “Many patients get deconditioned from sitting around not able to do anything and the drugs take their toll on heart, lung function and other organs in the body,” explains Dr. Courneya. “We aim to eliminate lingering symptoms like fatigue, depressive symptoms, peripheral neuropathy as well as improving fitness and quality of life.”
The motivated patient
Breast cancer survivor and retired McGill media communications professional Carole Grossman* is nearing her five-year milestone of being cancer-free and she credits exercise with getting her through chemotherapy. She was physically active prior to her diagnosis and, like other active individuals, she found it hard to imagine being inactive after her diagnosis. “There wasn’t a day that I ever allowed myself to stay in bed, even after chemo,” says Carole. “I made my bed, put on my Lululemons™ and went to the gym every single day,” she added.
“I believe that I got through my chemo treatments because of that,” Carole continued. “I didn’t do what I normally would have done but I did the best that I could. It helped with low appetite and the nausea that accompanies chemo. When you have cancer, you’re always living with the fear of recurrence but for me every day is a milestone because, let’s face it, it can come back any time. And that’s why I’m doing my best to make sure that it doesn’t.”
A stone that can kill two birds – just not necessarily at the same time
In the general population, the main benefit of PA is a reduction in cardiovascular disease. However, 25% of deaths are a result of cancer so PA is actually reducing the population’s risk of developing and dying from cancer or cardiovascular disease. But once you are diagnosed with cancer, the risk of death is driven heavily by the cancer itself. In some cancer patients, especially the ones with a very good prognosis, the risk of cardiovascular disease is higher. So for these patients, exercise can lower the risk of cancer recurring but also lower the risk of cardiovascular disease death by improving cardiovascular function.
Aiming for more precision
Until now, studies in this area have relied on participants’ self-reporting as the means of gathering data on their physical activity but the Alberta Moving Beyond Breast Cancer (AMBER) study is changing that. Co-led by Dr. Courneya, this study will be the first to use objective measures of physical activity. Participants will wear accelerometers—small devices that objectively measure participants’ movement—for a week. Dr. Courneya and his team will be able to measure how much time patients spend sitting, standing, and moving around. The device will also measure the pattern of movement over the course of the week. The researchers will examine cardiovascular fitness, lower body strength, upper body strength, and body composition.
“With the fitness data, we’re going to measure their aerobic fitness, muscular strength and body composition to see what might protect against dying from cancer,” explains Dr. Courneya. “We are going to be able to sort through the detailed aspects of activity patterns and fitness profile and see if we can identify an exercise pattern or fitness profile that is exceptionally good for lowering the risk of cancer recurrence and death,” says Dr. Courneya.
Recruitment for the study began in 2012 and is almost complete. The study itself will last five years and data will be available in five to seven years.
* Carole Grossman was in the audience when Dr. Courneya received his prize and gave a brief lecture on his research. She is not a participant in Dr. Courneya’s research.