The aim of this study was to investigate the clinicopathological characteristics and distribution by tumor localization of KRAS point mutations in metastatic colorectal cancer. A total of 189 patients diagnosed with colorectal cancer between 2007 and 2014, who were either metastatic at the time of diagnosis or developed metastasis subsequently, were included in this study. KRAS mutation analysis was performed in the primary tumor tissues and KRAS mutations were identified in 47.6% of the patients. There was a high frequency of the p.G13D point mutation in left-colon tumors (P=0.011), while the p.G12D point mutation was more frequent in right-colon tumors (P=0.004). KRAS wild-type frequency (P=0.02) was higher among patients aged <40 years. A comparison of codon 12 and 13 mutations revealed that codon 12 mutations were more common in the >50-year-old group (P=0.03) and codon 13 mutations were more common in the <70-year-old group (P=0.04). KRAS wild-type tumors were localized in the right colon (P=0.005) and tumors with the p.G13D point mutation (P=0.018) were diagnosed at non-metastatic stages. In conclusion, KRAS point mutations in colorectal cancer exhibited a heterogeneous distribution in terms of tumor localization. In addition, the p.G13D point mutation was found to differ from other mutations in several aspects.
Keywords: colorectal cancer; specific KRAS mutation; tumor location.