Authors' reply: "The obesity paradox in patients with colorectal cancer: a systematic review and meta-analysis".

This article addresses the discussion surrounding the "obesity paradox" in colorectal cancer, specifically the concern that collider bias—a type of selection bias—may explain why obese patients sometimes show better survival outcomes. The authors acknowledge collider bias as a possible factor but argue that it should not be considered the primary explanation, citing studies that adjusted for multiple confounders and still observed the paradox. They emphasize the need for large-scale prospective studies and sensitivity analyses, such as calculating E values, to assess unmeasured confounding and suggest future use of propensity score matching to mitigate bias. Overall, the article highlights ongoing debate about the obesity paradox’s underlying mechanisms and the importance of careful methodological approaches in related research.