The role of exercise in cancer management is being explored as a potential benefit, with a recent study suggesting that physical activity before diagnosis is associated with a decreased risk of the disease’s progression and death.
The results highlight the potential benefits of exercise for decreasing cancer progression risk and encourage its regular incorporation into people’s lives, said the scientists.
The findings, published in the British Journal of Sports Medicine, looked at how physical activity levels before cancer diagnosis affected cancer progression and mortality among participants in South Africa.
Including data from more than 28 000 participants with stage 1 cancers, the study found that physical activity before diagnosis could be tied to lower mortality and cancer progression.
Authors of the study noted that physical activity helps prevent cancer and decrease mortality, based on available evidence, but wanted to examine how it influenced cancer progression in South Africa, as data in this area are lacking.
Medical News Today reports that this research was a retrospective longitudinal observational study, using anonymised data from people on the medical plan Discovery Health Medical Scheme.
All participants were also part of the Vitality health promotion programme, which encourages exercise and allows physical activity to be recorded through wearable fitness devices and other actions like clocked gym attendance.
Researchers included participants in their analysis who had stage 1 cancer and had been in the Vitality programme for at least one year before their diagnosis. They also conducted a sub-analysis that excluded certain cancer types that were more likely to affect physical activity levels before diagnosis.
The average time participants were in the Vitality programme was nine-and-a-half-years.
There were divided into three groups based on physical activity levels:
none: no recorded physical activity;
low: 1-59 minutes of recorded physical activity a week; and
moderate to high: one hour or more of recorded physical activity a week.
For this study, physical activity meant at least moderate intensity, and researchers assigned participants into categories based on their physical activity in the 12 months before cancer diagnosis, although additional analysis considered earlier activity, too.
Researchers took into account age at diagnosis, sex, and socioeconomic status, which was based on factors like insurance type.
They also took into account the general impact of comorbidities before cancer diagnosis.
When looking at specific types of cancer, researchers performed separate analyses on the effects of physical activity on prostate, breast, and skin cancer.
Disease progression 27% less likely in physically active people
About 62% of participants had no recorded physical activity, but about 25% had moderate to high recorded physical activity. Prostate and breast cancer were the most common cancer types among participants.
Throughout the observed time frame, almost 19% of the participants died, but 65.5% of them did not experience cancer progression.
Compared with those with no activity, people in the moderate to high physical activity group were 27% less likely to experience cancer progression and 47% less likely to experience death from any cause.
The low physical activity group was 16% less likely to experience cancer progression and 33% less likely to experience death from any cause compared to the group with no physical activity.
However, when looking at participants who had body mass index data, there wasn’t a significant difference in progression outcomes for the low physical activity group and the no physical activity group.
Analyses of specific cancer types revealed similar benefits. But when it came to prostate cancer progression and skin cancer all-cause mortality, low physical activity levels had the most positive results. For skin cancer progression, the impact of low and moderate to high physical activity was the same.
When looking at the probability of progression and death, the data continued to highlight the benefits of physical activity. For example, two years after diagnosis, people who had moderate to high physical activity in the year before diagnosis had an 80% chance of not dying or cancer not advancing to higher levels.
By comparison, people with no physical activity had a 74% chance of these events not happening. When looking at all-cause death, people with no physical activity had a 91% chance of survival, while people with moderate to high physical activity had a 95% chance of survival.
Exercise and cancer progression: a causal relationship?
The research cannot establish a causal relationship, even though it points to the benefits of exercise. When looking at the probabilities of cancer progression and death, researchers used an example of a male individual with certain characteristics. This could have affected the results.
The recorded physical activity of participants could also differ from actual levels of physical activity.
While researchers minimised the risk of reverse causality, it is still possible.
There is also the possibility of bias because researchers did not adjust for factors like smoking. They also assumed participants who did not have recorded physical activity in the Vitality programme were not doing recreational exercise.
Anne McTiernan, MD, PhD, professor in the Epidemiology Programme at the Fred Hutchinson Cancer Centre McTiernan, said: “There were several drawbacks to the study: it only collected exercise data from before diagnosis. We have no idea what these patients did afterwards (…) While the measured exercise was probably accurate, it didn’t capture all that people do. So, for example, patients who had physically active jobs but didn’t wear watches that capture movement would have been inaccurately classified as doing no physical activity. The data support this since 60% were classified as having no physical activity. Even walking to your fridge or car or job entails some activity, so this study would have vastly underestimated amounts of activity.”
Researchers also lacked some data. For example, they had limited data on body mass index (BMI), so they did not account for this information in the primary analysis. They only examined it in a secondary analysis. They also did not have racial or ethnicity data for participants. Some participants also left the scheme.
Furthermore, the findings cannot necessarily be generalised to all people in South Africa since this focused on people with access to private health insurance, which tends to be higher among white and Asian descent individuals. Individuals were also part of an incentive programme that encouraged physical activity.
Researchers only considered three specific types of cancer in additional analyses and otherwise looked at all cancers together.
“The population was from an insurance database (…) The database was developed for insurance, not research. So other variables that could explain associations between exercise and prognosis (completion of cancer therapies, weight, smoking, etc.) were largely not available,” McTiernan added.
Overall, the results highlight the positive impact of exercise compared with sedentary behaviour when it comes to cancer progression and mortality. It suggests that even low levels of physical activity may be beneficial.
Study author Jon Patricios, MBBCh, MMedSci, a specialist sport and exercise medicine physician and visiting professor at Wits University, noted the following clinical implications of the data: “With cancers being diagnosed earlier and an increasing incidence, accessible interventions that may positively influence prognosis are more relevant than ever. 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.
“Regular physical activity is the most powerful and accessible prescription we can give our patients,” he added.
The study confirms the benefits of even relatively small amounts of physical activity “but we should encourage adherence to the WHO guidelines of 300 minutes per week of moderate intensity exercise”, he said.
Study details
Association between recorded physical activity and cancer progression or mortality in individuals diagnosed with cancer in South Africa
Ntokozo Mabena, Nivash Rugbeer, Sandra Lehmann, Georgia Torres, Deepak Patel, Mosima Mabunda, Mike Greyling, Jane Thornton, Yun-Hee Choi, Saverio Stranges, Jon Patricios.
Published in The BMJ in January 2025
Abstract
Objectives
This study aimed to determine the association between progression and mortality in individuals with stage 1 cancer and their recorded physical activity before the diagnosis of the cancer.
Methods
We included 28 248 members with stage 1 cancers enrolled in an oncology programme in South Africa. Physical activity was recorded using fitness devices, logged gym sessions and participation in organised fitness events. Levels of physical activity over the 12 months before cancer diagnosis were categorised as no physical activity, low physical activity (an average of <60 min/week) and moderate to high physical activity (≥60 min/week). Measured outcomes were time to progression, time to death and all cause mortality.
Results
Physically active members showed lower rates of cancer progression and lower rates of death from all causes. The HR for progression to higher stages or death was 0.84 (95% CI 0.79 to 0.89), comparing low activity with no physical activity, and 0.73 (95% CI 0.70 to 0.77), comparing medium to high physical activity with no physical activity. The HR for all cause mortality was 0.67 (95% CI 0.61 to 0.74), comparing low physical activity with no activity, and 0.53 (95% CI 0.50 to 0.58), comparing medium to high physical activity with no physical activity.
Conclusions
Individuals engaging in any level of recorded physical activity showed a reduced risk of cancer progression or mortality than those not physically active. There was a further reduction among individuals with moderate to high levels of physical activity compared with those with lower levels.
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Sedentary behaviour independently predicts cancer mortality