The Obesity Paradox in Cancer: Epidemiologic Insights and Perspectives

Purpose of Review: Controversy exists whether excess body fatness (measured by body mass index (BMI)) is associated with better cancer survival (“obesity paradox”). Here, we review the obesity paradox in cancer research and discuss potential explanations and future research directions. Recent Findings: Overweight and obese cancer patients have better survival for diverse cancers. This apparent obesity paradox may be largely explained by methodological limitations including reverse causation, selection bias, confounding, and reliance of BMI as a measure of adiposity in cancer patients. A growing number of studies show promising evidence that precisely quantified body composition can provide important prognostic information in cancer care, such that low muscle and high adiposity are associated with worse clinical outcomes in cancer patients. Summary: The term obesity paradox in cancer, implying a causally beneficial role of adiposity, is misleading. Understanding the role of muscle and adiposity may reduce the confusion and inform precision oncology care.