Raising awareness of obesity and physical activity in cancer risk
Researchers at Cancer Council NSW have reported that obesity and physical activity are independent risk factors of cancer. They have also examined in depth if the two factors interact. Their study found physical activity has the potential to lower someone’s cancer risk regardless of their body weight, highlighting the need to encourage physical activity separately from achieving a healthy weight.
Background
We know that one in three cancer cases can be prevented, with physical activity and obesity playing a role in this. Physical activity has many benefits. Besides fighting off weight gain and obesity, it can reduce insulin and insulin-like growth factors which can promote the growth of cancer cells.
Exercise is also likely to reduce exposure to dietary carcinogens (known to cause cancer) by speeding up food passing through the bowel. Being overweight on the other hand, significantly increases someone’s risk of 11 different types of cancer. Excess body weight increases the risk of insulin resistance, which leads to the pancreas producing more insulin.
The research
- The study of almost 9,000 participants aimed to find out how someone’s body weight would influence the protective effects that physical activity has on the risk of developing several different cancers.
- No interaction between the two factors was found – indicating that physical activity has the potential to lower someone’s cancer risk regardless of their body weight. The results suggest the benefits of physical activity can be experienced by all individuals in similar ways.
- The study also looked at how physical activity and obesity independently had an impact on someone’s risk for several different cancers and confirmed that high levels of physical activity decreased risk, while obesity increased it.
The impact
This study has important public health implications, as it shows the public should be encouraged to both be active and to achieve a healthy weight. People at a healthy weight sometimes perceive exercise as optional, but these findings show exercise may benefit everyone, irrespective of their body weight.
The high rate of obesity in Australia and its impact on cancer risk is a major concern. Cancer Council NSW hopes this research will inspire Australians to work towards a healthy weight, while also staying physically active. A healthy and balanced diet can be beneficial for both of these goals.
The study is also the first of its kind in Australia. Previous studies have looked at the role of physical activity and BMI in cancer risk, but very few have also explored the interaction between the two risk factors. The findings add another layer of evidence to other research which has shown a significant link between insufficient physical activity and increased cancer risk.
Research team
Carlos Nunez (Doctoral scholar)
The University of Sydney
Professor Adrian Bauman
Dr Visalini Nair-Shalliker
Sam Egger
Associate Professor Freddy Sitas