RAS, BRAF, and MMR system mutations in metastatic colorectal cancers: an observational study

Abstract

Introduction: Colorectal cancers (CRCs) are the second cause of malignancy-related deaths and over half of CRCs become metastatic. Genetics plays a critical role in understanding metastatic colorectal cancers (MCRCs), as various genetic mutations influence progression and treatment responses. While there exists plenty of research on genetic mutations in CRCs, few studies have focused on mutations in MCRC patients. The present study aims to provide an overview of the prevalence of KRAS, NRAS, BRAF, and MMR mutations in Iranian MCRC patients. Methods: The present study is a descriptive cross-sectional study on patients with MCRCs referred to a tertiary medical center in Iran from March 2015 to March 2022. Ethics approval was obtained from the ethics committee of the University of Medical Sciences. The patient’s MCRC was confirmed by pathology and Genotyping Assessments of tissue for KRAS, NRAS, BRAF, and MMR mutations. Results: A total of 136 MCRC patients were included in this study; 44 patients (40.7%) had KRAS mutations in their lesions. KRAS mutation status was not significantly related to age or gender (P > 0.05). Only one NRAS mutation was found in one patient. There were no cases of BRAF mutation identified. Among 48 patients assessed for MMRs deficiency, 8 cases (16.7%) were positive, 7 cases (14.6%) were MSI-H, and 1 case (2.1%) was MSI-L. Conclusion: Although no significant relation was found between the KRAS mutation pattern and gender, age, or tumor primary location, the MSI-H mutation-positive tumors were significantly more prevalent in younger patients.