Abstract
BACKGROUND: Metastatic colorectal cancer (mCRC) remains a major cause of cancer-related mortality, but few noninvasive biomarkers exist to track disease progression or inform treatment strategies. Circulating tumor cells (CTCs) offer a minimally invasive source of tumor material, yet the prognostic significance of their genomic diversity remains unclear. METHODS: We conducted whole-exome sequencing of CTC pools from 29 mCRC patients to characterize their mutational landscape and assess associations with overall survival. RESULTS: Our analysis revealed substantial variation in mutational burden among patients, with all CTC pools harboring non-silent mutations in key CRC driver genes. Higher genomic diversity in CTC pools was significantly associated with reduced overall survival. Additionally, non-silent mutations in BCL9L emerged as a strong predictor of patient survival. CONCLUSION: Genomic diversity and BCL9L mutational status in CTC pools emerged as strong predictors of survival in mCRC, underscoring the potential of CTC genomic profiling as a minimally invasive and clinically relevant prognostic tool in mCRC.