K-ras in Colorectal Cancer Tumors From Saudi Patients: Frequency, Clinco-pathological Association and Clinical Outcome

Background: K-ras oncogene mutations are confirmed factor for lack of clinical benefit from antibodies targeting EGFR in patients with colorectal cancer (CRC). Mutations are reported in 40% of CRC tumors in western patients. There is scarcity of data on population from Asia and the Middle East. Aims: This study investigates the frequency and impact of k-ras mutation and the association between clinico-pathological features and K-ras status in Saudi patients with CRC. Patients and Methods: Retrospective review of K-ras status, clinico-pathological characteristics and clinical outcome in 46 patients with CRC. Results: K-ras mutations were identified in 15/46 (32%) tumors, 87% at codon 12 and 13% at codon 13. Gender, site of tumor, stage at diagnosis, differentiation and lymphatic and vascular invasion were tested as potential risk predictors for K-ras status. Only gender was found to be a potential risk factor. Female gender compared to male posed higher significant chance of wild type status (RR=1.54, 65% CI: 1.07-2.2; P=0.034). K-ras status (mutant vs. wild) did not statistically significantly impact on clinical outcome as measured by development of relapsed disease (80% vs. 81%), median relapse free survival (17 vs. 11 months, P=0.256) and overall survival (not reached in both groups, P=0.59). Conclusion: This relatively small retrospective series shows that rate of K-ras mutation in Saudi patients with CRC is lower than reported in western Caucasian population but close to rates reported in neighboring Asian population. Mutations are less frequent in females. In these patients, K-ras mutation status did not significantly impact clinical outcome.