Clinico-Pathological Study of K-ras Mutations in Colorectal Tumors: A Single-Center Retrospective Study of 51 Patients in Madinah, Saudi Arabia.

Background Colorectal cancer (CRC) is one of the leading types of cancer worldwide and in Saudi Arabia. At the molecular level, CRC is very complicated and requires establishing comprehensive patient stratification models through identification of patients who will benefit or will not benefit from targeted therapy. We retrospectively investigated and analyzed the frequency of Kirsten-ras (K-ras) mutation and its correlation with patients' characteristics as weel as its association with clinicopathological features (i.e age, gender, clinical stage, anatomical site, histological subtype, degree of histological differentiation and metastatic site) in patients with CRC. Methods Medical records and paraffin-embedded tumor samples from 51 patients with histologically proven colorectal adenocarcinoma referred to Madinah center in Saudi Arabia were analyzed for the occurrence of rat sarcoma virus (RAS) mutations. Results RAS mutations occurred in 43% of the patients; 91% of these mutations were in K-ras. Seventy-five percent of these K-ras mutations were in codon 12, most commonly p.G12D. Codon 13 mutations occurred in 20% of tumors: all of these were p.G13D (100%). The percentage of K-ras mutations occurrence was higher in young patients (≤50) compared with the older patients (>50) (54.5% and 35%, respectively). Similarly, the percentage of K-ras mutations occurrence was higher in the right-sided tumors compared with the left-sided tumors (57.1% and 32.4%, respectively). Patients' characteristics and clinicopathological features were not significantly associated with K-ras mutations. Conclusions K-ras mutations are common among Saudi patients diagnosed with CRC in Madinah, especially pG12V and pG12D in codon 12. Further investigation would be required to establish correlation of K-ras mutations in larger cohorts.