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Review
. 2016 Sep;18(9):56.
doi: 10.1007/s11912-016-0539-4.

The Obesity Paradox in Cancer: a Review

Hannah Lennon  1   2 , Matthew Sperrin  3 , Ellena Badrick  4   3 , Andrew G Renehan  4   3
Affiliations
Review

The Obesity Paradox in Cancer: a Review

Hannah Lennon et al. Curr Oncol Rep. 2016 Sep.

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.

Keywords: Adiposity; BMI; Body mass index; Cancer; Cancer survival; Epidemiology; Excess weight; Mortality; Obesity; Overweight; Prognosis.

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Conflict of interest statement

Hannah Lennon, Matthew Sperrin, Ellena Badrick, and Andrew G. Renehan declare that they have no conflict of interest. Human and Animal Rights and Informed Consent This article does not contain any studies with human or animal subjects performed by any of the authors.

Figures

Fig. 1
Fig. 1
An illustration of the obesity paradox. The vertical axis represents hazard ratio of mortality (log scale), compared with the baseline BMI of 22.5 kg/m2. The plot represents a population in which the obesity paradox is observed, since the hazard ratio is below 1 in the overweight and obese range. The 95 % confidence intervals are shown with dashed lines
See this image and copyright information in PMC

Comment in

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