A recent study published in the British Journal of Cancer found evidence of a causal relationship between body mass index (BMI) and overall cancer risk and mortality and suggests that overall an increase in BMI causally increases the risk of developing and dying from cancer.
Researchers used a Mendelian randomisation (MR) approach to determine the causal effect of BMI in 46,155 white-British participants with any cancer type and 264,638 healthy individuals without cancer from the UK Biobank. They selected 6998 participants who died of cancer and 270,342 healthy control individuals for the mortality analysis and also identified 390,628 cancer-free participants with BMI data and weight measurement to derive MR instruments for BMI.
The overall risk for cancer (estimated causal OR [COR], 1.07; 95% CI, 1.02-1.12) and mortality (COR, 1.28; 95% CI, 1.16-1.41) was higher with per standard deviation (4.78-unit change) increase in genetically predicted BMI. Similar estimates were obtained for female and male separately. The overall cancer risk among smokers (COR, 1.07; 95% CI, 1.02-1.13) and non-smokers (COR, 1.04; 95% CI, 0.97-1.10) were higher but there was no significant difference in causal estimate of BMI on cancer risk between smokers and non-smokers (P=.43).
Based on the finding of this study, the authors said, “Small change in BMI may have a big impact on the reducing burden of cancer because of the high prevalence of obesity in the population. Although the estimated effect sizes for BMI were not large particularly for overall cancer risk, cancer prevention strategies targeting weight control must be continued, given the high prevalence of obesity”.