Low body mass index (BMI) may be associated with an increased risk of progression and death among patients with metastatic colorectal cancer (mCRC), according to a recent study published online ahead of print in the Journal of Clinical Oncology.1

Researchers led by Lindsay Renfro, PhD, of the Mayo Clinic in Rochester, MN, conducted a retrospective analysis of 21 149 patients with early-stage colorectal cancer who were enrolled in 25 first-line mCRC trials from 1997 to 2012.

They assessed for prognostic and predictive effects of low and high BMI on overall survival and progression-free survival while accounting for patient and tumor characteristics and therapy type.

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The researchers found that risk of progression and/or death was greatest among patients with low BMI, with decreasing risk as BMI increased up to approximately 28 kg/m2, when it plateaued.

Compared to obese patients, those with a BMI of 18.5 kg/m2 were found to have a 27% increased risk of having a PFS event and a 50% increased risk of death.

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Poorer survival was noted among men compared to women with low BMI, and BMI was not found to be predictive of treatment effect.

“Possible explanations include negative effects related to cancer cachexia in patients with low BMI, increased drug delivery or selection bias in patients with high BMI, and potential for an interaction between BMI and molecular signaling pathways,” the authors concluded.


  1. Renfro LA, Loupakis F, Adams RA, et al. Body mass index is prognostic in metastatic colorectal cancer: pooled analysis of patients from first-line clinical trials in the ARCAD database [published online ahead of print October 26, 2015]. J Clin. Oncol. doi: 10.1200/JCO.2015.61.6441.