New evidence that physical activity plays a key role in lowering the risk of death from cancer and reducing progression of the disease by more than a quarter has emerged from research in which Wits Sport & Health (WiSH) had a leading role.
The Wits research was built on findings published late last year in the British Journal of Sports Medicine. Data from the Discovery Health medical scheme, linked to its Vitality programme, was used in collaborative research with the University of Western Ontario.
Lead author Jon Patricios, a professor at Wits University and part of the division of sports & exercise medicine at WiSH, says: “Knowing that as little as 60 minutes of regular weekly exercise may reduce the likelihood of cancer progression by 27% and death by 47% should encourage all doctors to use exercise as medicine.”
Patricios says the study confirms the benefits of even relatively little physical activity, but urges adherence to the World Health Organisation guidelines of 300 minutes a week of moderate-intensity exercise.
The study included 28,248 Vitality members with stage 1 cancer, and looked at comprehensive physical activity data for the year preceding diagnosis from 2007 to 2022. Breast and prostate cancers were the most common, comprising 44% of the study.
The time between initial diagnosis and disease progression, death or exit from the study ranged from a month to almost 13 years.
The odds on disease progression were 16% lower for those who had engaged in low levels of physical activity in the preceding year than among those who had not recorded any physical activity.
Cancer did not progress in nearly two-thirds of the sample (65.5%) but did in just more than a third (34.5%). And while 81% survived, 19% of participants died before the end of the study. The average time to death was 20 months and the average time to progression was seven months.
Levels of physical activity in the year before diagnosis were categorised as none recorded (17,457; 62% of participants); low, equal to 60 or less weekly minutes (3,722; 13%); and moderate to high, equal to 60 or more weekly minutes of moderate-intensity physical activity (7,069; 25%).
After accounting for factors such as age at diagnosis, sex, economic and social position and coexisting conditions, rates of cancer progression and death from any cause were lower among those who were physically active in the year preceding their diagnoses.
The odds on disease progression were 16% lower for those who had engaged in low levels of physical activity in the preceding year than among those who had not recorded any physical activity. The odds for those engaged in moderate to high levels were 27% lower.
The odds on death from any cause were 33% lower among those who had done low levels of physical activity compared with those who had not, and 47% lower for those who had moderate to high levels.
Two years on from diagnosis, the likelihood of no disease progression among those with no recorded physical activity in the year before diagnosis was 74%, compared with 78% and 80% for those achieving low and moderate to high levels.
While the likelihood of disease progression increased in time, it was still lower for those who had clocked some physical activity in the year preceding a diagnosis. After three years, the likelihood of no disease progression was 71%, 75% and 78% for none, low and moderate to high levels of physical activity. And after five years it was 66%, 70% and 73%.
Similar patterns of death were evident from any cause. Two years after diagnosis, the probability of survival among those with no documented physical activity in the year preceding diagnosis was 91% compared with 94% and 95% among those who had recorded low and moderate to high levels. The equivalent probabilities of survival three years after diagnosis were 88%, 92% and 94%, and 84%, 90% and 91% after five years.
Patricios cautions that it was an observational study and so could not establish cause and effect. The researchers acknowledged that they were not able to account for other potentially influential factors such as smoking and alcohol consumption, while the data on weight was incomplete.
However, there are several plausible biological explanations for the findings, they suggest. Chief among these is the way in which physical activity strengthens immunity by increasing numbers of natural cancer killer cells, lymphocytes, neutrophils and eosinophils.
Physical activity may also lower the progression risk of hormone-sensitive cancers, such as breast and prostate cancers, by regulating oestrogen and testosterone levels, they add.
“Physical activity may be considered to confer substantial benefits in terms of progression and overall mortality to those diagnosed with cancer,” the researchers note.
“In a world where cancer continues to be a significant public health burden, the promotion of physical activity can yield important benefits regarding the progression of cancer as well as its prevention and management,” they conclude.
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