Cetuximab might be detrimental to metastatic colorectal cancer patients with KRAS codon 12 mutations

Background: Anti-epidermal growth factor receptor (EGFR) monoclonal antibodies benefit patients with wild-type KRAS exon 2 metastatic colorectal cancer (mCRC). However, their effect in KRAS-mutant mCRC remains unclear. Patients and Methods: This was a retrospective study enrolling 163 patients with unresectable KRAS-mutant mCRC diagnosed at the National Taiwan University Hospital between 2007 and 2011. Results: The median overall survival (mOS) was 29.5 months in patients who had never used cetuximab and 19.0 months in those who had (p=0.040). The mOS was 32.0 months in patients with mutant KRAS codon 12 who had never used cetuximab and 17.5 months in those who had (p=0.017). In patients with mutant KRAS codon 13, the mOS was not significantly different. Univariate and multivariate Cox proportional hazards analysis revealed that absence of cetuximab treatment was an independent prognostic factor for longer mOS in patients with unresectable KRAS-mutant mCRC. Conclusion: Cetuximab usage might be detrimental to patients with mCRC with mutant KRAS codon 12.