Abstract
There is a common perception that excess adiposity, commonly approximated by body mass index (BMI), is associated with reduced cancer survival. A number of studies have emerged challenging this by demonstrating that overweight and early obese states are associated with improved survival. This finding is termed the “obesity paradox” and is well recognized in the cardio-metabolic literature but less so in oncology. Here, we summarize the epidemiological findings related to the obesity paradox in cancer. Our review highlights that many observations of the obesity paradox in cancer reflect methodological mechanisms including the crudeness of BMI as an obesity measure, confounding, detection bias, reverse causality, and a specific form of the selection bias, known as collider bias. It is imperative for the oncologist to interpret the observation of the obesity paradox against the above methodological framework and avoid the misinterpretation that being obese might be “good” or “protective” for cancer patients.
Highlights
Excess body adiposity is a major global public health problem, with 67 % of the US, % of the UK, and % of Australia’s population being classified as overweight or obese, by body mass index (BMI) criteria, in 2014 [1]
In a meta-analysis of 29 studies evaluating the impact of BMI on survival in patients with colorectal cancer, Wu et al [30] observed that increasing pre-diagnosis BMI prognosticated for a poor survival but that post-treatment overweight was associated with improved survival, i.e., the obesity paradox
This review has highlighted the mixed findings in studies evaluating the obesity paradox in cancer populations
Summary
Excess body adiposity is a major global public health problem, with 67 % of the US, % of the UK, and % of Australia’s population being classified as overweight or obese, by body mass index (BMI) criteria, in 2014 [1]. There is a common perception that, compared with normal-weight patients, elevated BMI is associated with poorer prognosis after cancer diagnosis. This certainly is observed in systematic reviews of the literature among women with breast cancer [4] and forms a key rationale for weight management recommendations among cancer survivors, endorsed by clinical guidelines, for example, by the American Society of Clinical Oncology [5], with similar recommendations from the American Cancer Society [6] and European Society for Medical Oncology [7].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
