Prognostic value of KRAS exon 2, exon 3 and exon 4 mutations in colorectal cancer patients

Abstract

The clinical significance of many RAS-family mutations in colorectal cancer (CRC) remains unclear. The purpose of this study was to investigate the relationship of mutations on an exon basis (i.e., mutations in KRAS exons 2, 3 and 4 and in NRAS) with clinicopathological features and prognosis in CRC. We performed a retrospective cohort study of the medical records and frozen tissue samples of 268 consecutive patients with stage I-III CRC who underwent curative resection at a single institution in 2014–2018. The RAS mutation rate was significantly associated with age and histology. Patients with KRAS exon 2 mutations exhibited shorter RFS compared to those with KRAS wild-type, KRAS exon 3 mutations, KRAS exon 4 mutations and NRAS mutations (73.0% vs. 85.5%, 86.7%, 85.7%. p = 0.031). Age and histology were independent risk factors for RAS mutations. RAS mutations were independent prognostic factors with respect to RFS in patients with stage I–III CRC. In stage I–III CRC patients, KRAS exon 2 mutations have the worst prognosis, while RAS wild type, RAS exon 3 mutations, RAS exon 4 mutations and NRAS mutations have better prognoses.