ASSOCIATION BETWEEN SMOKING AND KRAS STATUS IN METASTATIC COLORECTAL CANCER

Mohammad Ahmad Telfah*, Mohammad Said Alkader, Habeeb Lutfi Etewi, Manar Hasan Hayajneh and Ahmad Taher Alkhladi

ABSTRACT

Backgroung: Colorectal cancer (CRC) is one of the most common cancer worldwide and affecting the mortality, Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation is the most common mutation in CRC, its occurrence may reach 45% of all CRC. Detecting KRAS mutation predicts the response of treatment. Smoking can affect the molecular subtype of CRC such as KRAS wild type, raf murine sarcoma viral oncogene homolog B (BRAF) mutant, microsatellite instability-high (MSI-H), and 5’-C-phosphate-G-3’ island methylator phenotype (CIMP) positive tumors. Material & Methods: This retrospective study analyzed the medical records of 129 mCRC diagnosed between 2017 and 2022 at the Military Cancer Center (MCAC). The clinical and pathological characteristics of the patients were recorded, including age, gender, primary tumor location, smoking, KRAS status and metastatic site. Results: most of the patients had left sided tumor 107 (82.9%), KRAS mutations were detected in 52 patients (40.3%), the most common mutation was gly12asp in 19 patients, and 59 patients (45.7%) were smokers. the most of smoking patients were associated with KRAS wild type (72.9%), while 34 patients (48.8%) were not smoker (P=0.005). the site of tumor is associated with KRAS status, KRAS was wild type in 8 patient (36.4%) in the right side tumor, while 69 patients (64.5%) were KRAS wild type in left side tumor (P=0.01). Left sided colorectal cancer had a more risk to develop KRAS wild type than right sided colorectal cancer (OR= 3.71, 95%CI: 1.36 – 10.2, P=0.01), and smoker patients were at more risk to have wild type colorectal cancer than not smoker patients (OR= 3.16, 95%CI: 1.46 – 6.87, P=0.004). Conclusion: smoking and left sided tumor are associated with KRAS wild type CRC, and both of them increase its risk.

Keywords: colorectal cancer, metastatic colorectal cancer, KRAS mutant, KRAS wild type, smoking.