The obesity paradox in cancer: clinical insights and perspectives

The obesity paradox refers to the paradoxical relationship between obesity and instances of better long-term survival in cancer, given the huge body of evidence for obesity’s carcinogenic effects. This article, published in Eating and weight disorders- studies on anorexia, bulimia and Obesity, seeks to explore the available studies concerning cancer incidence, survival and obesity in order to offer possible explanations for the paradox and a methodological framework.

The potential mechanisms highlighted for the ‘obesity paradox’ are that obesity provides a nutritional reserve, helping the patient survive surgical interventions and anti-cancer treatments. Also, that obesity is associated with a lower-stage of disease, smaller tumour size and less aggressive subtypes. Finally, that obese patients are likely to be frequent users of healthcare, therefore cancer may be diagnosed sooner.

There are however, methodological issues with these explanations. The issue of BMI, which is a proportional score based on weight and height, gives no information regarding body composition which is important in cancer care. Furthermore, the overall literature that supports this relationship, uses mainly retrospective studies and often fails to include confounding variables such as age and smoking. Rigorous prospective studies need to be conducted to define the impact of obesity in the oncology setting.