New research highlights the potential impact of maintaining physical activity levels as we age – and the importance of understanding the relationship between movement, sedentary behaviour and cancer risk.
Physical activity is already recognised as an important component of cancer prevention, with evidence linking higher levels of activity with a reduced risk of several cancers, including bowel, breast, bladder, kidney and stomach cancers.
Now, research from University College London (UCL) has added further weight to the relationship between daily movement and cancer risk, suggesting that even relatively small changes in physical activity levels could have an impact.
Published in BMC Medicine, the study analysed data from 59,218 participants in the UK Biobank, with an average age of 61.7 years. Over approximately eight years of follow-up, 2,385 participants were diagnosed with cancer.
The researchers used lifestyle data alongside theoretical modelling to examine what might happen when periods of physical activity were replaced by sedentary behaviour, sleep or lower-intensity movement.
The analysis identified a dose-response relationship: higher levels of physical activity were associated with lower cancer risk. Replacing 15 minutes of inactivity or sleep with 15 minutes of physical activity was associated with a 2% reduction in cancer risk.
Conversely, replacing 30 minutes of physical activity with sedentary behaviour was associated with an 8% increase in risk, while replacing activity with additional sleep was associated with a 7% increase.
Importantly, these findings should not be interpreted as evidence that losing a specific number of minutes of exercise will directly cause cancer. The study is based on observational data and modelling, meaning that the results demonstrate an association rather than establishing a direct causal relationship.
Nevertheless, the findings reinforce an increasingly important message: maintaining physical activity may be particularly important as people get older.
Why does physical activity matter?
The relationship between physical activity and cancer is complex and involves multiple biological pathways.
Regular movement can contribute to maintaining a healthy body weight and metabolic function, while also influencing inflammation, immune function, insulin and hormone levels. These processes can all play a role in cancer development and progression.
Physical activity may also reduce the amount of time people spend sedentary. Prolonged sedentary behaviour has itself been associated with poorer health outcomes, making the balance between movement and inactivity an important consideration alongside formal exercise.
The latest research is therefore less about a particular “15-minute rule” and more about the cumulative effect of everyday activity.
The importance of maintaining activity
The researchers found that even among people who were already physically active, reducing their activity levels was associated with increased cancer risk in the modelling.
This is particularly relevant as populations age. Maintaining mobility and physical activity can become more challenging because of changes in health, fitness, work patterns and lifestyle.
The study’s lead author, Dr John Mitchell of UCL, emphasised the importance of maintaining activity levels among people who are already physically active as they get older.
This does not necessarily mean undertaking intense exercise every day. The findings sit alongside existing evidence supporting a broad range of physical activities and the benefits of reducing prolonged periods of sitting.
From population research to prevention
The UCL study is another example of how large-scale health datasets can help researchers identify relationships between lifestyle factors and disease risk.
However, translating population-level associations into individual recommendations requires careful interpretation. Factors such as age, existing health conditions, diet, smoking, body weight and other lifestyle characteristics can influence both physical activity levels and cancer risk.
For researchers and healthcare professionals, the challenge is therefore to understand not only whether activity is associated with cancer risk, but also how much activity, what type and at what stage of life may provide the greatest benefit.
For the pharmaceutical and life sciences sectors, this broader understanding of cancer prevention is equally important. As cancer research increasingly moves towards earlier intervention, risk reduction and personalised approaches, understanding the multiple factors that influence cancer development will remain central to improving outcomes.
The latest findings provide another reminder that cancer prevention is rarely about a single intervention. Instead, it is shaped by a complex interaction between biology, behaviour, environment and healthcare – with physical activity representing one potentially modifiable part of that picture.
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