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Exercise across the cancer continuum

Exercise across the cancer continuum
Hello, and welcome to this step on exercise across the cancer continuum. In this video, we will examine the strength of the evidence to date on benefits associated with physical activity across the cancer continuum, from prevention through treatment and into survivorship. When examining evidence on the effects of physical activity on health related parameters, it is important to note that lower levels of evidence, or more uncertainty, does not necessarily mean that the effects of physical activity are weaker, or that exercise is less effective in that area. It may simply indicate that there is not enough evidence to make a definite conclusion. To start, let us examine the strength of evidence on the role of physical activity in the prevention of cancer.
The World Cancer Research Fund Global Network has a vision to help people make choices that reduce their chances of developing cancer. To achieve this vision, they support expert panels in reviewing evidence of cancer prevention. Of the 10 current recommendations that this group have published on preventing cancer, one is to reduce body fatness and be as lean as possible without being underweight. Another is to be physically active as part of everyday life. Since physical activity protects against overweight and obesity, it is easy to appreciate how exercise has a strong role to play in cancer prevention. In this video, we will discuss the role of physical activity. However, it is important to note that sedentary behavior may independently increase cancer risk.
Alarmingly, the International Agency for Research on Cancer estimates that 25% of cancer cases worldwide are caused by overweight or obesity and a sedentary lifestyle.
Since the 1990s, evidence on the association between physical activity and cancer has been accumulating. Overall, despite variability between study populations and methodologies, the evidence in favor of physical activity in the prevention of cancer is consistent. We know that sustained physical activity is protective against cancers. This effect may be more pronounced for certain cancer sites, however, some argue that between the effects of physical activity alone, and the resultant decreases in body fat often accompanied by increased physical activity, all activity is beneficial in cancer prevention. Furthermore, we know that physical activity does not increase the risk of any cancers. This leads us to question how much exercise is required.
In general, the evidence suggests that there’s a dose response relationship between cancer prevention and physical activity. This means that, with the exception of extreme levels of activity, the more physically active people are, the better. Of the many different types of cancer, physical activity is most protective against colorectal cancer, post-menopausal breast cancer, and endometrial cancer. Interestingly, evidence suggests that for these cancers, physical activity is protective independently of body fatness. Reductions in body fat reduce the risk of several other cancers, including liver, prostate, ovarian, gall bladder, kidney, esophageal, and pancreatic. Now let us consider the role of exercise in cancer survivorship. Historically, health care professionals advised cancer survivors to rest and to avoid activity.
Evidence has since accumulated to challenge this recommendation, and today, cancer survivors who are physically able, are advised to reach the general public physical activity guidelines, unless they have been advised otherwise. Cancer survivors are defined as people who are living with a diagnosis of cancer, and includes those receiving treatment, in recovery, and those who have had a full recovery from cancer. Cancer survivors are often at risk of becoming sedentary for several reasons. The population of survivors is several million and growing, and this population can reap important health benefits from engaging in physical activity.
Exercise prescription needs to be individually tailored for those with cancer and should follow careful assessment. This is important since many cancer treatments are toxic and can result in short and long term effects relevant to exercise prescription, such as decreased fitness, suppressed immune function, and pain. Despite these challenges, the American College of Sports Medicine state that it is safe for patients with cancer to exercise, both during and after cancer treatments. There are numerous evidence-based reasons for cancer survivors to exercise. These include improved quality of life, improved physical functioning, and reduced cancer-related fatigue. Exercise helps cancer survivors cope with and recover from their treatment.
Furthermore, exercise may reduce the risk of cancer recurrence or slow cancer progression, reduce the risk of second primary cancers, and other chronic diseases. There is also evidence to suggest that exercise can help alleviate some common cancer related symptoms and side effects of cancer treatments, such as lack of appetite, diarrhea, paresthesia, constipation, fatigue, muscle pain, arthralgia, depression, anxiety, and insomnia. Finally, and perhaps most impressive, is the evidence to suggest that exercise makes standard survival in this cohort. Similar to cancer prevention, the evidence in cancer survival shows a dose response relationship between health benefits and volume of physical activity. In other words, the more physical activity, the better. Let us take a closer look at the evidence for specific cancer sites.
When examining the strength of evidence on the benefits of exercise, level A denotes that the evidence is overwhelming and has come from well-executed, randomized controlled trials. Level B indicates that the evidence comes from randomized controlled trials, but that these trials are smaller, and results across trials may have been inconsistent. There is level A evidence that exercise is safe during and after treatment for breast cancer and prostate cancer. For those with breast cancer, there is also level A evidence that physical activity and exercise lead to improvements in aerobic fitness and muscle strength, both during and after treatment. There is level B evidence that exercise can improve body composition, anxiety, fatigue, and quality of life, both during and after treatment.
For those with prostate cancer, there is level A evidence that exercise leads to improvements in aerobic fitness, muscular strength, and fatigue during and after treatment. Furthermore, there is level B evidence that exercise can improve body composition, quality of life, and physical function during and after treatment. There is less evidence available for other populations, however, it is worth noting that all of the available studies in other populations, the evidence suggests that exercise is safe and effective at improving aerobic fitness and muscular strength. In fact, evidence in this area consistently states that appropriately prescribed exercise results in multiple benefits for cancer survivors.

In this video, Cuisle describes the benefits of exercise for patients across the cancer continuum. A startling statistic from the International Agency for Research on Cancer describes that 25% of cancer cases worldwide are caused by overweight or obesity and a sedentary lifestyle.

As we saw in Mr Kenna’s experience in Week 1, exercise can be beneficial for patients with cancer.

Fatigue is a consideration when prescribing exercise to cancer survivors.

  • Can you think of any other exercise related consideration specific to cancer survivors?
Note: This video refers to how exercise can help prevent certain cancers, and how exercise can be of benefit to cancer survivors. With regards to exercise for those who have been diagnosed with cancer (cancer survivors) please note that this video and the evidence base from which the material cited in it is drawn, does not advocate using exercise as the only form of treatment for cancer but rather to complement medical, pharmaceutical and surgical interventions where necessary as part of a multidisciplinary care package.
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Exercise Prescription for the Prevention and Treatment of Disease

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