Body Mass Index and Cancer
In the News – August 20, 2014
The Journal LANCET has published a very large study (Over 5 million individuals) examining the link between high body mass index (BMI) and 22 common cancers. Increased BMI appeared to be “roughly linearly associated” with increased risk of cancers of the uterus, thyroid, gallbladder, kidney, cervix and leukemia. There was also a positive association with liver, colon, ovarian and post menopausal breast cancer.
Interestingly, BMI appeared to be inversely associated with prostate and premenopausal breast cancers. The authors conclude that “Assuming causality, 41% of uterine and 10% or more of gallbladder, kidney, liver, and colon cancers could be attributable to excess weight.”
The problem here, as always with these studies, is that association doesn’t prove causality. One could reasonably assume that overweight status might also be associated with other unhealthy factors such as unhealthy diet, sedentary lifestyle, alcohol consumption etc. The authors did look at the effects of smoking in their analysis, but the study stopped well short of adjusting for many other variables.
Mark R. Payne DC
Reference: Bhaskaran K, Douglas I, Forbes H, et al. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5·24 million UK adults. The Lancet. 2014; doi:10.1016/S0140-6736(14)60892-8.