<![CDATA[BACKGROUND: Colorectal cancer (CRC) is a major global health problem associated with high cancer-related mortality. Profiling of Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation status has become a decisive predictive biomarker in the management of CRC. However, KRAS mutation testing is commonly performed using tumor tissue obtained through invasive biopsy or surgery; therefore, fecal DNA analysis might offer a promising non-invasive alternative. This study was conducted to evaluate the concordance of KRAS mutations between matched tumor tissue and fecal samples and their association with clinicopathological characteristics.METHODS: This cross-sectional study included 94 patients confirmed of CRC. Tumor tissue specimens were obtained during surgical resection or biopsy, while fecal samples were collected pre-operatively. KRAS mutations were analyzed using polymerase chain reaction (PCR) and DNA sequencing, and the associations with clinicopathological variables were statistically evaluated.RESULTS: KRAS mutations were detected in 45.74% of tumor tissue and 26.60% of fecal samples. The overall concordance rate was 65.96%, with a Cohen’s Kappa of 0.291 (95% CI: 0.110–0.472), indicating "fair agreement". Notably, allele-specific concordance was 100% among double-positive cases. The fecal assay demonstrated 41.86% sensitivity, 86.27% specificity, 72.00% positive predictive value (PPV), and 63.77% negative predictive value (NPV). Tumor location (colon versus rectum) was significantly associated with fecal KRAS detection (p=0.028); other variables showed no significant association (p>0.05).CONCLUSION: KRAS mutations were more frequently detected in tissue than in fecal samples, with fair agreement. High allele-specific concordance suggests fecal DNA accurately reflects the tumor's mutational profile. Tumor location significantly influences DNA detectability, supporting fecal-based KRAS testing as a potential non-invasive approach for CRC molecular assessment.KEYWORDS: colorectal neoplasms, feces, KRAS protein, human, mutation, neoplasm tissue]]>
