Cancers attributable to dietary factors in the UK in 2010

The relative risk of meat consumption for colorectal cancer is taken from the WCRF report (2007) , and is based on the effect of red meat in a meta-analysis of three prospective studies (1.29 per 100 g red meat per day). Under the assumption that the increase in risk is a logarithmic function of intake of meat, the risk is increased by 0.0025 for each gram of meat consumed. The effect of processed meat, based on five studies, was 1.21 per 50 g per day (the excess risk corresponds to 0.0038 per gram). The latent period, or interval between ‘exposure’ to meat and the increased risk of colorectal cancer, is not known. In the cohort studies included in the meta-analyses by WCRF (2007) , the mean duration of follow-up was 8.9 years. In studies contributing to the meta-analysis by Larsson and Wolk (2006) , the mean duration of follow-up (when this was given) was 8.7 years. We chose to assume a mean latency of 10 years, and estimate the effects on cancers occurring in 2010 from meat consumption in 2000. Information on consumption of meat in the UK is available for 2000–2001 from the National Diet and Nutrition Survey ( Food Standards Agency, 2002 ) as mean consumption, in grams of different types of meat per week, by age group and sex. The relevant data are shown in Table 1 . The population distribution of protein consumption, in grams per day, by age group and sex, is available from the National Diet and Nutrition Survey (Volume 2, Table 3.1; Food Standards Agency, 2003 ). This was converted to grams of meat per day, based on the average intake of meat ( Table 1 ) and protein (NDNS Volume 2, Table 3.4) in each age–sex group. The estimate for 2000 is shown in Table 2 (as the percentage of the population in different age–sex groups consuming specified amounts of red and processed meat), and in Figure 1 as the cumulative frequency (percentage) of the population in each age–sex group at different consumption levels. Estimated consumption of red and processed meat, by age group and sex, expressed as grams per day. The relative risk of meat consumption for each of the x consumption categories shown in Table 2 was calculated according to the following formula: where R g is the increase in risk of colon cancer per gram of meat (0.0025) and G x is the consumption of meat in gram per day in category x . Population-attributable fractions (PAFs) were calculated for each sex–age group according to the following formula: where p x is the proportion of population in consumption category x and ERR x the excess relative risk (RR x −1) in consumption category x . Table 3 shows PAFs of colorectal cancer resulting from meat consumption in 2000–2001, and the estimated number of cases ‘caused’ in 2010. The final three columns show the excess numbers of cases of colorectal cancer caused by meat consumption expressed as a fraction of the total burden of (incident) cancer. The estimate is 3.5% cancers in men and 1.9% in women, or 2.7% of cancers overall.