More than 2,500 cancer cases a week could be avoided | Cancer Research UK | March 2018
Cancer Research UK has published findings which demonstrate that almost 4 in 10 ( 37.7 per cent) of cancers could have been prevented. The landmark study highlights that many lifestyle factors could contribute to an individual’s risk of developing cancer. The study identifies 135, 500 cases of cancer a year in the UK that could be prevented through lifestyle changes. The research findings have been published this month in the British Journal of Cancer (the full abstract at the end of the post).
While smoking was to blame for the largest percentage of preventable cancer cases, using data from 2015 the researchers observed, tobacco smoke caused around 32,200 cases of cancer in men (17.7% of all male cancer cases) and around 22,000 (12.4%) in women.
Obesity is the second highest contributory risk to developing cancer: around 22,800 (6.3%) cases of cancer a year are down to being overweight or obese. This is equivalent to around 13,200 (7.5%) cases of cancer in women and around 9,600 (5.2%) in men. The results imply that 5% (1 in 20) cancer cases might possibly be prevented by maintaining a health weight. Obesity has been linked to 13 different types of cancer, such as cancers of the bowel, breast and kidney.
The third greatest factor in preventable cancers was overexposure to UV radiation from the sun and sunbeds, associated with around 13,600 cases of melanoma skin cancer a year, 3.8% of all cancer cases.
Other preventable lifestyle risks outlined in the study were eating too little fibre causing around 11,900 cases equivalent to 3.3% each, drinking too much alcohol (attributed to causing 11,700 cases or 3.3% each.
In repsonse to the findings of the research, Sir Harpal Kumar, Cancer Research UK’s chief executive, said: “Leading a healthy life doesn’t guarantee that a person won’t get cancer, but it can stack the odds in your favour. These figures show that we each can take positive steps to help reduce our individual risk of the disease.” (Cancer Research UK)
Full press release from Cancer Research UK here
Full reference: Brown, K. F., et al | 2018 | The fraction of cancer attributable to modifiable risk factors in England, Wales, Scotland, Northern Ireland, and the United Kingdom in 2015 |British Journal of Cancer | doi:10.1038/s41416-018-0029-6
Changing population-level exposure to modifiable risk factors is a key driver of changing cancer incidence. Understanding these changes is therefore vital when prioritising risk-reduction policies, in order to have the biggest impact on reducing cancer incidence. UK figures on the number of risk factor-attributable cancers are updated here to reflect changing behaviour as assessed in representative national surveys, and new epidemiological evidence. Figures are also presented by UK constituent country because prevalence of risk factor exposure varies between them.
Population attributable fractions (PAFs) were calculated for combinations of risk factor and cancer type with sufficient/convincing evidence of a causal association. Relative risks (RRs) were drawn from meta-analyses of cohort studies where possible. Prevalence of exposure to risk factors was obtained from nationally representative population surveys. Cancer incidence data for 2015 were sourced from national data releases and, where needed, personal communications. PAF calculations were stratified by age, sex and risk factor exposure level and then combined to create summary PAFs by cancer type, sex and country.
Nearly four in ten (37.7%) cancer cases in 2015 in the UK were attributable to known risk factors. The proportion was around two percentage points higher in UK males (38.6%) than in UK females (36.8%). Comparing UK countries, the attributable proportion was highest in Scotland (41.5% for persons) and lowest in England (37.3% for persons). Tobacco smoking contributed by far the largest proportion of attributable cancer cases, followed by overweight/obesity, accounting for 15.1% and 6.3%, respectively, of all cases in the UK in 2015. For 10 cancer types, including two of the five most common cancer types in the UK (lung cancer and melanoma skin cancer), more than 70% of UK cancer cases were attributable to known risk factors.
Tobacco and overweight/obesity remain the top contributors of attributable cancer cases. Tobacco smoking has the highest PAF because it greatly increases cancer risk and has a large number of cancer types associated with it. Overweight/obesity has the second-highest PAF because it affects a high proportion of the UK population and is also linked with many cancer types. Public health policy may seek to mitigate the level of harm associated with exposure or reduce exposure levels—both approaches may effectively impact cancer incidence. Differences in PAFs between countries and sexes are primarily due to varying prevalence of exposure to risk factors and varying proportions of specific cancer types. This variation in turn is affected by socio-demographic differences which drive differences in exposure to theoretically avoidable ‘lifestyle’ factors. PAFs at UK country level have not been available previously and they should be used by policymakers in devolved nations. PAFs are estimates based on the best available data, limitations in those data would generally bias toward underestimation of PAFs. Regular collection of risk factor exposure prevalence data which corresponds with epidemiological evidence is vital for analyses like this and should remain a priority for the UK Government and devolved Administrations.