Low body mass index (BMI) may be associated with a higher risk of progression and death among patients with metastatic colorectal cancer (mCRC) enrolled in clinical trials, according to a meta-analysis published in the Journal of Clinical Oncology.1

Researchers led by Lindsay Renfro, PhD, of the Mayo Clinic in Rochester, MN, looked at individual data from 21,149 patients who were enrolled in 25 first-line mCRC trials during 1997 to 2012.

They assessed for prognostic and predictive effects of BMI on the overall and progression-free survival (PFS) of these patients while accounting for patient and tumor characteristics as well as therapy type.

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The researchers found that risk of progression and death was greatest among patients with low BMI, with a steadily decreasing risk as BMI increased up to 28 kg/m2. Low BMI was also found to be associated with poorer survival in men than woman.

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Compared to obese patients, patients who had 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.

“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.