K-ras mutational status and its clinical implications in Korean colorectal cancer patients.

Abstract

641 Background: The incidence of K-ras mutation of exon 2 was reported between 30-40% in colorectal cancer, and it is well known predictive biomarker for EGFR monoclonal antibody. However, its prognostic role has not been defined so far, especially in Eastern country. Methods: From January 2007 to September 2013, patients who were diagnosed as colorectal cancer and examed K-ras exon 2 mutation in Saint Vincent’s hospital were retrospectively reviewed. Results: Among 436 patients, 343 patients with sufficient clinical information were analyzed. The median follow up period was 13.0 (0.2-94.8) months. The incidence of K-ras mutation was 37.9% (codon 12 mutation: 28.6%, codon 13 mutaiton: 9.0%, both: 0.3%). Codon 12 p.G12D was most frequent (52.3%), and codon 13 p.G13D was the next (22.3%). The presence of K-ras mutation was associated with old age (p=0.038), female gender (p=0.034), lesser nodal involvement (p<0.001), but not related to stage, tumor site, and histology. There is no significant clinical differences between codon 12 and 13 mutations. The recurrence free survival in patients who received curative resection was worse in patients with K-ras mutation (p=0.001). The prognostic role of K-ras mutation was more prominent in colon cancer, while it lost its prognostic significance in rectal cancer. Conclusions: The prognostic role of K-ras mutation was different according to primary tumor sites in colorectal cancer.