Search

This retrospective study investigated the clinical characteristics of patients with metastatic colorectal cancer (mCRC) depending on the KRAS status, thereby differentiating KRAS exon 2 mutations in codon 12 versus codon 13. In total, 273 patients with mCRC receiving first-line therapy were analyzed. One hundred patients were treated within the FIRE-3 trial (FOLFIRI plus cetuximab or bevacizumab), 147 patients within the AIO KRK-0104 trial (cetuximab plus CAPIRI or CAPOX), and further 26 patients received therapy outside the study. Thirty-eight tumors with KRAS mutation in codon 13, 140 tumors with mutation in codon 12, and 95 tumors with KRAS wild type as a comparison were included in this analysis. Bivariate analyses demonstrated significant differences between KRAS wild-type, codon 12-mutated, and codon 13-mutated tumors with regard to synchronous lymph node metastasis (P=0.018), organ metastasis (76.8% vs. 65.9% vs. 89.5%, P=0.009), liver metastasis (89.5% vs. 78.2% vs. 92.1%, P=0.025), lung metastasis (29.5% vs. 42.9% vs. 50%, P=0.041), liver-only metastasis (48.4% vs. 28.8% vs. 28.9%, P=0.006), and metastases in two or more organs (49.5, 61.4, 71.1, P=0.047). Regression models indicated a significant impact of KRAS mutations in codon 12 versus codon 13 for synchronous organ and nodal metastasis (P=0.01, 0.03). This pooled analysis indicates that mCRC is a heterogeneous disease, which seems to be defined by KRAS mutations of the tumor. Compared with KRAS codon 12 mutations, codon 13-mutated mCRC presents as a more aggressive disease frequently associated with local and distant metastases at first diagnosis.