Elderly couple eating watermelon symbolising a healthier lifestyle through nutrition

Preventing cancer through our lifestyle choices

8 September 2021
Dr John Schoonbee, CMO, SwissRe

Dr John Schoonbee

Chief Medical Officer, Swiss Re

Over the past 18 months, we've seen the power of modifying our behaviours (wearing masks, socially distancing, getting vaccinated etc.) to keep ourselves and our communities safe from contagion and illness. COVID-19 has also revealed how everyday lifestyle choices leading to obesity, insulin resistance and diabetes can significantly increase the likelihood of COVID-19 hospitalisation and death.[1] 

These lifestyle choices can also affect the probability of developing cancer, a leading cause of mortality worldwide. As our lives (hopefully) slowly transition back to a somewhat more “normal” state, what lessons did we learn about the power of behaviour change? Are people more aware of the interconnection between everyday decisions and habits and long-term health outcomes? Are they more willing to modify their lifestyles to reap health benefits? Could the key to preventing many cancers really be as simple as adapting our lifestyles? 

At Swiss Re, we fondly refer to these modifiable health behaviours as "The Big Six" Lifestyle Risk Factors and we've narrowed our focus to six of the most prominent components: sleep, physical activity, nutrition, substance use, mental wellbeing and the environment. We focus on these factors because people can relate to them, they can be modified and are straightforward to track and measure – whether that be seamlessly, via wearables (apps, smartwatches, etc.), or by asking an individual.

We also zoom in on these six lifestyle factors because there is strong scientific evidence regarding their role in certain diseases, particularly cancer. In fact, some researchers have found that only 5-10% of all cancer cases can be attributed to genetic defects. In other words, 90-95% of cancer diagnoses can have their roots in the environment and lifestyle factors.[2] It is generally thought that up to half of cancers could be avoided through behavioural change and other preventive measures. 

All six of the lifestyle factors can play a role in reducing the risk of getting cancer, through three key modalities: reducing exposure to carcinogens including tobacco products, building a stronger immune system and reducing inflammation. I want to highlight two factors in particular: physical activity and nutrition.

On the activity front, research suggests that low levels of physical activity may increase the risk of developing colon or breast cancer, by upwards of 20‒30% (compared to high levels of activity).[3] Activity strengthens the immune system and plays a key role in increasing insulin sensitivity and improving metabolic health – less inflammation, and lower risk of diabetes and obesity – both known risk factors for many cancers. But it's important to note that activity doesn't necessarily require vigorous exercise. Even just reducing sedentary behaviour by engaging every week in two and half hours of moderate-intensity aerobic activity such as walking, for example, can make a difference when it comes to cancer risk and overall health improvements.

In regards to food choices, many populations are eating more and more processed foods as a percentage of energy intake.[4] A large study found that for a 10% increment in the proportion of ultra-processed food consumed, the risk of overall cancer increased by 11%.[5] By avoiding ultra-processed food and added sugar (like in sodas and artificial fruit juice) we can significantly reduce cancer risk.

Unfortunately, we know more about what we shouldn't eat than what we should. That's why nutritional researchers are focusing on the quality of food and an individual's approach to eating, rather than prescribing exactly what to eat. This requires people to be more thoughtful about their food. I like to call this “nutritional mindfulness” and it includes behaviours like avoiding sugar and ultra-processed foods, looking at nutrition facts labels (being aware of what foods contain), eating home-cooked meals more often and using fresh, whole (unrefined) ingredients.  

The beauty of the big six lifestyle factors is we are in control and can alter them (for the most part). We can reduce our likelihood of developing cancer and other diseases by making small changes to our everyday activities… whether it be walking more, practicing mindfulness, eating better, reducing our alcohol consumption, avoiding tobacco products, mitigating air pollution exposure or getting better sleep. Let's remember that small changes don't equate to easy changes. Changing something you do every day is hard. These patterns and preferences are often ingrained in us over decades and are often reinforced by our cultures, families, peers and societal norms. But it's not impossible and there are clear, tried-and-tested winning strategies as my behavioural science colleagues explain

But, adopting a healthier lifestyle is easier for people who live, work and exist in environments that support healthy behaviours. We must come together as a community to support long-term sustainable lifestyle change. Only then can we truly make a dent in reducing cancer incidence. 



[1] Gao, Min et al. "Associations between body-mass index and COVID-19 severity in 6·9 million people in England: a prospective, community-based, cohort study". The Lancet Diabetes and Endocrinology, vol 9, 6 (2021): 350-359
[2] Anand, Preetha et al. “Cancer is a preventable disease that requires major lifestyle changes". Pharmaceutical research, vol. 25,9 (2008): 2097-116. 
[3] Swiss Re Institute. "Move! Physical activity and its effect on morbidity and mortality risk". 2020. 
[4] Martínez Steele, Eurídice et al. "Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study". BMJ, 2016 Mar 9;6(3):e009892
[5] Fiolet, Thibault et al. "Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort". BMJ 2018;360:k322

Dr John Schoonbee is Chief Medical Officer at SwissRe, a medical doctor who has been working in the insurance field for about 20 years and directly for reinsurers since 2005. He is involved in many aspects of life insurance, including product development, risk and claims assessment, as well as helping with pricing some of the more complex medical life and health products.

Last update: 
Wednesday 8 September 2021