Biomarker testing and mutation prevalence in metastatic colorectal cancer patients in five European countries using a large oncology database.

Background: The literature on biomarker testing for metastatic colorectal cancer (mCRC) in Europe is scarce. This study aimed to estimate the percentage of mCRC patients from five European countries tested for biomarkers over time. Materials & methods: An oncology database was retrospectively analyzed; evaluated biomarkers were RAS, BRAF and microsatellite instability (MSI). The patients were drug treated during 2018 and tested for relevant biomarkers in 2013-2018. Results: RAS testing was conducted in >90% of mCRC patients from 2014 onwards. BRAF testing increased from 31% of mCRC patients in 2013 to 67% in 2018. MSI testing increased from 10 to 41%. There was no notable trend over time for RAS and BRAF mutation or MSI-high prevalence. Conclusion: Biomarker testing among patients diagnosed with mCRC was increased over time. This study demonstrates the quick uptake of biomarker testing in clinical practice. These findings are significant as biomarker-based drugs are becoming more common.