Is obesity an advantage in patients with colorectal cancer?

Obesity/higher BMI appears to be important determinants in the development of colon cancer as well as in predicting outcomes in the adjuvant setting in these patients. These associations seem to be stronger for men and tend to be 'J-shaped', with worse outcomes in both lower and upper BMI categories than in the middle categories. How this factors in the metastatic setting is less clear. A recent pooled analysis of patients with metastatic colorectal cancer receiving bevacizumab in the first-line setting observed that patients with the lowest BMI had the lowest median overall survival. An incremental BMI increase of 5 kg/m(2) led to actually a decrease in the risk of death (hazard ratio, 0.911 [95% CI, 0.879-0.944]). The observed association does not necessarily mean that obesity is an advantage for patients with metastatic colorectal cancer. More likely, it is conceivable that, in patients with metastatic colorectal cancer with a lower BMI, the effects of cancer-related cachexia may be more deleterious than the potential adverse events related to a higher BMI. In patients already diagnosed with metastatic disease, studying how body weight affects tumor biology and treatment-related decisions are important considerations.