The Importance of Biomarker Testing in mCRC

Precision medicine has become fundamental in treating metastatic colorectal cancer (mCRC), with comprehensive molecular testing now required for every patient before initiating treatment. Leading oncologists emphasize that upfront genomic profiling must include BRAF V600E status, RAS status, microsatellite instability (MSI) status, and fusion detection. The evolving landscape now requires knowledge of specific KRAS mutation types, particularly G12C versus non-G12C mutations, as these distinctions impact both current treatment decisions and future clinical trial eligibility.

Health care systems face practical challenges in implementing comprehensive genetic testing, including coordinating between internal laboratories and external partners, ensuring results are properly documented in electronic medical records, and maintaining accessibility across different platforms. Experts recommend incorporating molecular profiles into every patient note and tracking dynamic changes throughout the treatment trajectory. The type of assay used, and timing of testing should be carefully documented, as these factors may influence treatment decisions and future therapeutic options.

Treatment timing remains a critical consideration when waiting for molecular test results. While some oncologists advocate for starting FOLFOX chemotherapy in urgent clinical situations while awaiting comprehensive genomic results, others recommend delaying treatment for appropriate clinical trial opportunities. The consensus emphasizes individualizing decisions based on disease burden, patient symptoms, and available clinical trials. Liquid biopsy serves as a valuable backup when tissue samples are insufficient for comprehensive genomic analysis, ensuring no patient misses targeted therapy opportunities.