Background: Understanding population-level exposure to cancer risk factors is vital when devising risk-reduction policies. By reducing exposure to cancer risk factors, many cancers could be prevented. But what impact on cancer incidence do these risk factors have? And what proportion of cancers could be prevented if these risk factors are avoided? Aim: The aim of this analysis was to update the estimates of the number and proportion of theoretically preventable cancers in the UK to reflect the changing behavior as assessed in representative national surveys, and new epidemiologic evidence. Separate estimates were also calculated for England, Wales, Scotland, and Northern Ireland because prevalence of risk factor exposure varies between them. Methods: 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. Results: Around four in ten (38%) cancer cases in 2015 in the UK were attributable to known risk factors. The proportion was around two percentage points higher in UK males (39%) than UK females (37%). Comparing UK countries, the attributable proportion for persons was highest in Scotland (41%) and lowest in England (37%). Tobacco smoking contributed by far the largest proportion of attributable cancer cases, followed by overweight and obesity, accounting for 15% and 6%, respectively, of all cases in the UK in 2015. Conclusion: Around four in ten (38%) cancer cases in the UK could be prevented. Tobacco and 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. 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 reduce the level of harm associated with exposure or reduce exposure levels - both approaches may be effective in preventing cancer. The variation in PAFs between UK countries is affected by sociodemographic 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 the devolved nations to develop more targeted public health measures. This analysis demonstrates the importance of nationally representative exposure prevalence data and cancer registration in informing evidence-based public health policy.
Geographical Patterns in Drug-Related Mortality and Suicide: Investigating Commonalities in English Small Areas
