Somatic mutations in colorectal cancer: regional experience

Abstract

Introduction. Colorectal cancer is one of the most common malignant neoplasms in economically developed countries, ranking 3rd and 2nd in the structure of morbidity and mortality, respectively. Current knowledge about the molecular features of colorectal cancer is necessary to implement the principle of personalized therapy.
 Aim. To study regional features of tumor genomic landscape in colorectal cancer.
 Materials and methods. The retrospective study from 2019 to 2022 included 153 patients with stage IIV colorectal cancer aged 32 to 80 years, with a median of 63.8 years. DNA samples extracted from paraffin blocks of tumor tissue were analyzed using a real-time polymerase chain reaction. The study patients included 43.8% of males and 56.2% of females.
 Results. Somatic mutations were detected in 48.4% of patients. The maximum number of mutations was detected in the KRAS gene 60 (81%). The mutation rate was significantly higher in females versus males. KRAS mutations predominate in the colon compared to the rectum, accounting for 66.7 and 33.3%, respectively. In tumors of the right colon, these mutations were detected in 18.3% of cases, and in the left colon, 48.4%. NRAS mutations were found in 9.5% of cases, mainly in tumors of the left colon. BRAF mutations were diagnosed in 6 patients, 5 of them were women, and the tumors were localized in the right colon. The highest rate of KRAS mutations was observed in codons 12 and 13, accounting for 86.7% of cases. The G12V mutation occurred in the majority of patients (25%), followed by G12D (20%) and G12A (16.6%).
 Conclusion. Somatic mutations in RAS and BRAF genes in colorectal cancer were detected in 48.4% of patients in the Tambov region. Among them, there is a predominance of KRAS mutations 81% in females. KRAS oncogenic mutations are predictors of treatment response and prognosis.