Obesity and Cancer
In their report on Diet, Physical activity and Cancer, the World Cancer Research Fund showed a clear association between BMI and death from cancer with an increase of more than 3.5 fold for those with a BMI over 40.0.
I came across a more recent paper (1) which summarised the role of obesity in multiple cancers. The numbers represent the relative risk for each cancer. For example, the risk of esophageal cancer is increased approximately 1.5 times for an increase in BMI of 5 kg/m².