It is well known that obesity is a risk factor for kidney cancer. However, a recent study finds that people with kidney cancer who are overweight or obese tend to live longer than those who are normal weight or under-weight.
The researchers investigated 4 databases of over 9,000 people with advanced kidney cancer. In one database of nearly 2,000 people with advanced kidney cancer, those who were obese or overweight survived for an average of nearly 26 months, while those of normal weight lived for around 17 months. In addition, overweight patients were 16 percent less likely to die during the study period. There were similar findings from the other 3 databases.
The researchers could not find any differences in the DNA from the kidney cancer tumours, such as gene mutations, that might account for the findings. However, obese patients had less fatty acid synthase (FASN) in their cells than normal-weight people. FASN is an essential protein (enzyme) that helps cells use genetic information to make fatty acids. High levels of FASN have been found in many types of cancer and are associated with poor outcomes. The decreased amount of FASN in obese and overweight kidney cancer patients might explain why obese patients have better outcomes. However, it is not known why these people produce less FASN.