Cancer Research UK : Bodyweight and risk of cancer in the UK

Bodyweight and risk of cancer in the UK

There is convincing evidence that being overweight or obese increases cancer risk1. Estimates suggest that, in the UK, up to about 12,000 cases of cancer (more than 4% of all cases) could be avoided if no-one exceeded a body mass index (BMI) of 252. Table 2.1 summarises what we currently know about overweight, obesity and risk of cancer.

Table 2.1: Overweight, obesity and cancer risk - summary

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The best evidence for a relationship between cancer and excess bodyweight is for cancers of the endometrium, kidney, oesophagus and colon and for breast cancer in post-menopausal women (Figure 2.1).

Figure 2.1: Proportion of selected cancers caused by overweight and obesity

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Obesity increases the risk of developing endometrial cancer by two to four-fold and the risk increases linearly with increases in BMI above 253. Obesity also increases the risk of breast cancer in post-menopausal women by up to 30%4,5. By contrast, pre-menopausal women with a BMI of 31 or more have been shown to have a 46% reduced risk of breast cancer, compared with women whose BMI is less than 21.5 This risk reduction may be because obesity can disrupt ovulation6.

A likely mechanism for the increased risk for breast and endometrial cancer in overweight women is that fatty tissue alters the levels of sex steroids. In men and post-menopausal women, fatty tissue is a major site for synthesis of oestrogens. Obesity can also increase concentrations of oestradiol in the plasma by reducing levels of sex-hormone binding globulin caused by higher insulin production and insulin-like growth factor I activity. Breast cancer risk is also affected by age at menarche and height, both of which are influenced by bodyweight earlier in life6.

The risk of colon cancer increases by about 60% in men and 30% in women with a BMI greater than 28.5, compared with a BMI under 223. Research suggests that obese men have a 90% increased risk of dying from colon cancer and the risk increases by between 23% and 37% in obese women7. Central obesity may be a better indicator for colon cancer risk than BMI.8 High levels of physical activity can reduce or remove the effect of obesity on the risk of colon cancer7.

Obese people have double the risk of renal cell cancer and adenocarcinoma of the oesophagus and gastric cardia, and an increased risk of gallbladder cancer3. Two recent large prospective studies in America support an association between obesity and pancreatic cancer9,10.

In Britain, a total of 67% of men and 52% of women have a BMI of 25 or more: this includes 25% of men and 20% of women who are obese (Figure 2.211)12.

Figure 2.2: Bodyweight of British adults, 1993 and 2002

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In the last ten years there have been significant increases in levels of overweight and obesity11. One in ten British men and one in four British women report dieting to lose weight12. Trends among children and young people suggest that we are yet to experience the full health impact of the overweight and obesity epidemic in the UK.

References

Diet, Nutrition, and the Prevention of Chronic Disease: Report of a joint WHO/FAO expert consultation, in WHO Technical Report Series. 2002, World Health Organisation/Food and Agriculture Organization: Geneva.
Bergstrom, A., et al., Overweight as an avoidable cause of cancer in Europe. Int J Cancer, 2001. 91: p. 421-430.PubMed
Bianchini, F., R. Kaaks, and H. Vainio, Overweight, obesity, and cancer risk. Lancet Oncol, 2002. 3(9): p. 565-74.PubMed
Lahmann, P.H., et al., Body size and breast cancer risk: Findings from the European prospective investigation into cancer and nutrition (EPIC). Int J Cancer, 2004. 111(5): p. 762-71.PubMed
van den Brandt, P.A., et al., Pooled analysis of prospective cohort studies on height, weight, and breast cancer risk. Am J Epidemiol, 2000. 152(6): p. 514-27.PubMed
Key, T.J., et al., Diet, nutrition and the prevention of cancer. Public Health Nutr, 2004. 7(1A): p. 187-200.PubMed
Murphy, T.K., et al., Body mass index and colon cancer mortality in a large prospective study. Am J Epidemiol, 2000. 152(9): p. 847-54.PubMed
Moore, L.L., et al., BMI and waist circumference as predictors of lifetime colon cancer risk in Framingham Study adults. Int J Obes Relat Metab Disord, 2004. 28(4): p. 559-67.PubMed
Michaud, D.S., et al., Physical activity, obesity, height, and the risk of pancreatic cancer. JAMA, 2001. 286(8): p. 921-9.PubMed
Patel, A.V., et al., Obesity, recreational physical activity, and risk of pancreatic cancer in a large U.S. Cohort. Cancer Epidemiol Biomarkers Prev, 2005. 14(2): p. 459-66.PubMed
Department of Health. Health Survey for England: Trend data 1993-2002. [Summary of key findings] 2003 Accessed Link
Office for National Statistics, The National Diet and Nutrition Survey: adults aged 19-64 years. 2003/2004.Link