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 target- ing 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 signifi- cant 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. Muta- tions are less frequent in females. In these patients, K-ras mutation status did not significantly impact clinical outcome.