16. The fraction of cancer attributable to lifestyle and environmental factors in the UK in 2010

TLDR

Population‑attributable fractions quantify the impact of risk factors on cancer, aiding prioritisation of control strategies. The chapter estimates the proportion of UK cancers in 2010 attributable to 14 lifestyle and environmental risk factors. The authors calculated attributable fractions for 18 cancer types using 14 risk factors and noted that projecting intervention impact requires complex scenario modelling of realistic population distributions, exposure timescales, latent periods, and post‑intervention change rates. Sub‑optimal exposure to the 14 risk factors accounted for 42.7% of UK cancers in 2010 (≈134,000 cases), with tobacco smoking alone responsible for 19.4% (60,000 cases); the remaining burden varied by sex, with fruit and vegetable deficiency, occupational exposures, and alcohol most important in men, and overweight/obesity and infections in women.

Abstract

This chapter summarises the results of the preceding sections, which estimate the fraction of cancers occurring in the UK in 2010 that can be attributed to sub-optimal, past exposures of 14 lifestyle and environmental risk factors. For each of 18 cancer types, we present the percentage of cases attributable to one or all of the risk factors considered (tobacco, alcohol, four elements of diet (consumption of meat, fruit and vegetables, fibre, and salt), overweight, lack of physical exercise, occupation, infections, radiation (ionising and solar), use of hormones, and reproductive history (breast feeding)). Exposure to less than optimum levels of the 14 factors was responsible for 42.7% of cancers in the UK in 2010 (45.3% in men, 40.1% in women) – a total of about 134 000 cases. Tobacco smoking is by far the most important risk factor for cancer in the UK, responsible for 60 000 cases (19.4% of all new cancer cases) in 2010. The relative importance of other exposures differs by sex. In men, deficient intake of fruits and vegetables (6.1%), occupational exposures (4.9%) and alcohol consumption (4.6%) are next in importance, while in women, it is overweight and obesity (because of the effect on breast cancer) – responsible for 6.9% of cancers, followed by infectious agents (3.7%). Population-attributable fractions provide a valuable quantitative appraisal of the impact of different factors in cancer causation, and are thus helpful in prioritising cancer control strategies. However, quantifying the likely impact of preventive interventions requires rather complex scenario modelling, including specification of realistically achievable population distributions of risk factors, and the timescale of change, as well as the latent periods between exposure and outcome, and the rate of change following modification in exposure level.