Exercise before a cancer diagnosis reduces disease progression and the risk of death

Exercise before a cancer diagnosis reduces disease progression and the risk of death

Regular physical activity before a cancer diagnosis may reduce the risk of disease progression and death, research published online suggestsBritish Journal of Sports Medicine.

And even relatively low levels of physical activity can be beneficial, the results show.

There is convincing evidence that physical activity plays a key role in reducing the risk of dying from cancer, but the evidence is not as conclusive about its role in disease progression, the researchers explain.

To investigate this further, they analyzed anonymized data from the Discovery Health Medical Scheme (DHMS), which is linked to the health promotion program Vitality. The DHMS is the largest open health insurance plan in South Africa, covering approximately 2.8 million beneficiaries.

All participants in the Vitality program are rewarded for a healthy lifestyle, earning points for physical activity recorded by activity trackers, logging visits to the gym or registered participation in organized fitness activities.

The type, frequency, duration and intensity of the activity are recorded and converted into weekly training minutes.

A total of 28,248 Vitality Program members with stage 1 cancer and comprehensive physical activity data for the year prior to diagnosis were included in the study, which spanned 2007 to 2022.

Breast and prostate cancer were the most common cancers, accounting for 44% of all study participants.

The time between initial diagnosis and disease progression, death, or withdrawal from the study ranged from one month to nearly 13 years.

In almost two-thirds of the total sample (65.5%) the cancer did not progress, but in just over a third (34.5%) it did. And while 81% survived, 19% died before the study ended. The median time to death was 20 months and the median time to progression was 7 months.

Physical activity in the year before diagnosis was classified as not recorded (17,457; 62% of participants); low, equal to 60 or fewer weekly minutes (3722;13%); and moderate to high, equal to 60 or more weekly minutes of moderate-intensity physical activity (7069; 25%).

Controlling for potentially influential factors such as age at diagnosis, gender, economic and social status, and comorbidities, rates of cancer progression and death from all causes were lower among those who were physically active in the year before diagnosis.

The odds of disease progression were 16% lower among those who had engaged in little physical activity in the previous year compared to those who had not recorded any physical activity, while the odds were 16% lower for those who had exercised moderately to vigorously and 27% lower.

Likewise, the odds of dying from any cause were 33% lower among those who had engaged in low levels of physical activity than among those who had no physical activity, and 47% lower among those who had achieved moderate to high levels of physical activity.

Two years after diagnosis, the likelihood of the disease not progressing was 74% among those who had no physical activity in the year before diagnosis, compared to 78% and 80% among those who achieved low and moderate-to-high levels of physical activity, respectively.

While the likelihood of disease progression increased over time, it was still lower among those who achieved some level of physical activity in the year before their diagnosis.

At 3 years, the probability of no disease progression was 71%, 75%, and 78% for no, low, and moderate-to-high physical activity, respectively. And after 5 years it was 66%, 70% and 73% respectively.

Similar patterns were evident in deaths from all causes. Two years after diagnosis, the probability of survival was 91% among those who had no documented physical activity in the year before diagnosis, compared with 94% and 95% among those who had recorded low and moderate-to-high levels, respectively.

The corresponding survival probabilities at 3 years after diagnosis were 88%, 92%, and 94%, respectively, and 84%, 90%, and 91%, respectively, at 5 years.

Because this is an observational study, cause and effect cannot be determined. And the researchers admit they were unable to take into account other potentially influential factors such as smoking and alcohol consumption, while data on weight (BMI) was incomplete.

However, they suggest that there are several plausible biological explanations for the results. The most important of these is the way physical activity strengthens the immune system by increasing the number of natural killer cells, lymphocytes, neutrophils and eosinophils.

They add that physical activity can also reduce the risk of progression of hormone-sensitive cancers such as breast and prostate cancer by regulating estrogen and testosterone levels.

“Physical activity can be expected to confer significant benefits in terms of progression and all-cause mortality in cancer patients,” they write.

“In a world where cancer continues to pose a significant public health burden, promoting physical activity may provide important benefits in terms of cancer progression, prevention and treatment,” they conclude.

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