Moreover, the analysis shows that even at relatively low levels of practice, the advantage is already significant and adds to the already convincing evidence of the key and beneficial role of physical activity in reducing the risk of death from cancer and in health outcomes and survival.
The study analyzes anonymised data from the Discovery Health Medical Scheme (DHMS), South Africa’s medical scheme which covers approximately 2.8 million beneficiaries. This system has implemented a program to encourage the adoption of a healthy lifestyle, Vitality. Vitality participants are rewarded by earning points for physical activity, recorded by activity trackers, attending a gym or participating in fitness activities. The researchers took into account the type of activity, frequency, duration and intensity of the activity practiced by each participant, for a total of 28,248 participants, followed from 2007 to 2022.
- Among the cancer diagnoses recorded, those of breast and prostate cancer were the most common, representing 44% of the total of these diagnoses;
- time from initial diagnosis to disease progression, death, or study withdrawal ranged from 1 month to almost 13 years;
- the cancer did not progress in almost two thirds of the sample (65.5%), but progressed in the other participants (34.5%);
- 81% of participants were alive at the end of follow-up;
- the average time from diagnosis to death was 20 months and the average time from diagnosis to cancer progression was 7 months;
- after taking into account possible confounding factors, including age at diagnosis, sex, economic and social situation and comorbidities,
- rates of cancer progression and death are significantly lower among participants who were physically active in the year before diagnosis;
- specifically, the risk of disease progression is reduced by 16% with low levels of physical activity in the previous year and by 27% with moderate and high levels of physical activity;
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the risk of death from all causes is reduced by 33% with low levels of physical activity in the previous year and by 47% with moderate and high levels;
- 2 years after diagnosis, the probability of absence of progression of the disease in people who had not practiced physical activity during the year preceding diagnosis is 74%, vs. 78% and 80%, respectively. , with low and moderate to high levels of physical activity;
- If the risk of cancer progression increases, logically, over time, it always remains lower if a certain level of physical activity is practiced during the year preceding diagnosis;
- similar trends are observed for deaths from all causes;
- the probabilities of survival 3 years after diagnosis are respectively 88%, 92% and 94% for the different activity levels (no, a little and moderate + high), and 84%, 90% and 91% at 5 years.
This observational study does not demonstrate cause and effect but leads to conclusions justifiable by numerous plausible biological explanations: the main one being the way in which physical activity strengthens immunity by increasing the number of natural killer cells, lymphocytes, neutrophils and eosinophils.
“In a world where cancer continues to represent a significant public health burden, promoting physical activity can provide important benefits.”
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