Somatic Mutation Landscape of Colorectal Cancer in Nigerian Patients: A Targeted Next-Generation Sequencing Study

Colorectal cancer (CRC) is increasingly recognised as an important cancer burden in Nigeria, yet the somatic mutation landscape of CRC in Nigerian patients is entirely uncharacterised at the molecular level. Understanding driver mutations is essential for prognosis, therapeutic targeting, and hereditary cancer risk assessment. This study characterised the somatic mutation landscape of CRC in Nigerian patients using a targeted NGS panel. Fifty formalin-fixed paraffin-embedded (FFPE) CRC tissue blocks were obtained from the pathology archives of the Lagos University Teaching Hospital and the National Hospital Abuja. A 57-gene cancer panel targeting common CRC driver genes (APC, KRAS, NRAS, BRAF, PIK3CA, TP53, SMAD4, and FBXW7) was sequenced on the Illumina MiSeq platform. Microsatellite instability (MSI) status was determined using a validated MSI primer panel. KRAS mutations were the most frequent somatic alterations, followed by TP53. BRAF V600E, which predicts response to anti-EGFR therapy, was detected at a lower frequency than reported in European CRC cohorts. High MSI was identified in 14 percent of cases, with implications for immunotherapy eligibility. These findings establish the first somatic mutation data for CRC in Nigerian patients and have direct therapeutic implications. Keywords: colorectal cancer, somatic mutation, targeted sequencing, KRAS, Nigeria