Defining obesity in the context of cancer: thinking beyond body mass index.

Obesity is a condition of excess body fat. Although it has been identified as a risk factor for multiple cancers in part because of its 'metainflammatory' state, it has also been paradoxically associated with improved response to immune checkpoint inhibition. To study obesity, one must first understand how best to define it. In this opinion article, we briefly discuss factors that are impacting net effects of obesity and highlight complementary measures that should be considered beyond body mass index (BMI) when attempting to assess the potential effects of obesity in cancer.