Health experts have estimated that 184,000 people in the UK will be diagnosed with preventable cancers this year and that it will cost the country just over £78bn. What are preventable cancers? They are cases of cancer that experts believe have developed as a result of what they call “modifiable risk factors”. Risk factors include smoking, heavy drinking, poor diet and sunburn. Evidence suggests that about two in five cases of cancer, in the UK and worldwide, are preventable. The World Cancer Research Fund (WCRF), which tracks evidence about what causes the disease, said: “When we talk about a cancer being attributable to a particular risk factor, it means there is strong evidence that the risk factor causes that cancer to occur. For example, 80-90% of lung cancers are attributable to smoking and so would be prevented if nobody smoked.” What are ‘modifiable risk factors’? These are factors that are “to a greater or lesser extent under the control of the individual”, the WRCF says. They involve people’s lifestyles. According to the WCRF, they include “smoking/consuming tobacco products; UV radiation/sun exposure; eating a healthy diet, including appropriate levels of fibre, fruit and vegetables and red and processed meat; avoiding consuming alcohol; meeting recommended physical activity levels per week; maintaining a healthy body weight, which is generally considered to be a body mass index below 25, although this level is different for those from racial and ethnic minority populations; and protecting oneself against infections such as HPV, HIV and hepatitis.” How many cancers are preventable? The WCRF says: “When these [risk] factors alone are considered, around 40% of cancers are considered preventable. This means that if everyone was able to follow the recommendations related to each of the above factors, 40% of cancers would be prevented at a population level. In short, four in every 10 cancers would not occur.” That 40% figure is fairly consistent across developed countries, research has found. How many cancer cases in the UK are preventable? Research published in the medical journal Nature in 2018 by Katrina Brown and others found that 37.7% of all cancers in the UK were attributable to known risk factors. That was the case for 38.6% of cancers in men and 36.8% of cancers in women. Scotland had the highest proportion of such cases among the four home nations at 41.5%. England had the lowest at 37.3%. What are the main risk factors? Alcohol, smoking, diet and UV radiation exposure are the biggest risk factors. Alcohol was classed as a carcinogen by the World Health Organization’s cancer agency back in 1988. It caused almost 17,000 cancers in the UK in 2020 and is a risk factor for seven forms of cancer including breast, mouth, liver and oesophageal (foodpipe) cancer. With smoking, Hazel Cheeseman, of Action on Smoking and Health, says: “Smokers’ bodies are exposed to a cocktail of carcinogens which increases the risk of developing at least 16 different cancer.” About 17,500 cases of melanoma skin cancer are diagnosed in the UK every year. Cancer Research UK estimates that with people holidaying in hot places, that could rise to 26,500 by 2038. Being overweight or obese can cause 13 different types of cancer, according to Dr Kawther Hashem, a lecturer in public health nutrition and campaign lead for Action on Sugar. It is the second biggest cause of cancer in the UK after smoking and is implicated in the development of about one in 20 cancer cases. The heavier the person is, the greater their risk of weight-related cancer. A study published in the Lancet last year found that almost half of cancer deaths globally were due to risk factors. Smoking, alcohol and a high body mass index were the biggest contributors. What can people do to minimise their risk of cancer? Michelle Mitchell, Cancer Research UK’s chief executive, said: “On an individual level there are a range of things that people can do to reduce their cancer risk, including not smoking, keeping a healthy weight, staying safe in the sun, cutting back on alcohol and eating a healthy balanced diet. Though cancer is more common as we get older, it’s never too early, or too late, to start making these healthy changes.”