Impact of Body Mass Index on Survival and Treatment Outcomes of Metastatic Colorectal Cancer
A pooled analysis of 25 studies with patients in the first line of treatment for metastatic colorectal cancer (mCRC) evaluated the prognostic and predictive significance of body mass index (BMI). Until its publication in 2015, only the adverse impact of low and high BMI on outcomes in patients with early stages of colorectal cancer was known.
Analyzed Data
This retrospective analysis included 21,149 patients from studies conducted between 1997 and 2012. It examined the relationship between BMI and progression-free survival (PFS) and overall survival (OS), considering patient characteristics, tumor characteristics, and type of treatment (targeted vs. non-targeted).
Findings
The median follow-up for patients was 18.9 months, with a median OS of 17.9 months and a median PFS of 8.8 months. The average BMI was 26.0 kg/m2. Underweight (BMI < 18.5 kg/m2) was found in 3.1% of patients, normal weight (BMI 18.5–25 kg/m2) in 42.8%, overweight (BMI 25–30 kg/m2) in 36.3%, and obesity (BMI > 30 kg/m2) in 17.8% of patients.
The results showed a prognostic impact of BMI on OS and PFS with an L-shaped curve. Specifically, the highest risk of disease progression or death was observed in patients with the lowest BMI, the risk decreased with increasing BMI up to a value of 28 kg/m2, and then plateaued. Compared to patients with obesity, patients with underweight had a 27% higher risk of disease progression or death and a 50% higher risk of death. Low BMI was significantly associated with shorter survival in men compared to women (p < 0.001).
Regarding treatment outcomes, the impact of BMI on PFS and OS did not differ between patients with and without targeted therapy.
The adverse prognostic impact of low BMI is consistent with results in patients with early-stage CRC. In these patients, obesity also had an adverse prognostic impact, which was not observed in the case of mCRC.
Conclusion
In this large pooled analysis, low BMI was an adverse prognostic factor in patients with mCRC. The risk of tumor progression or death was higher with low BMI and was more pronounced in men than in women. Conversely, no predictive impact of BMI was observed depending on the administration/non-administration of targeted therapy.
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Source: Renfro L. A., Loupakis F., Adams R. A. et al. Body mass index is prognostic in metastatic colorectal cancer: pooled analysis of patients from first-line clinical trials in the ARCAD database. J Clin Oncol 2016; 34 (2): 144−150, doi: 10.1200/JCO.2015.61.6441.
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