Integrating ctDNA testing for EGFR analysis in advanced non-small cell lung cancer: strategies for clinical laboratories.

Epidermal growth factor receptor gene (EGFR) molecular testing is essential for guiding targeted therapies in patients with advanced non-small cell lung cancer (NSCLC). Between 15 and 40 % of patients with NSCLC carry mutations in EGFR that are sensitive to tyrosine kinase inhibitors (TKIs). Due to the significant clinical benefits, identifying patients eligible for TKI therapy is crucial for optimizing treatment. While tumor tissue has been considered the gold standard for this testing, adequate material for EGFR molecular study cannot be obtained in up to 30 % of patients. In this context, circulating tumor DNA (ctDNA) analysis offers a guideline-recommended non-invasive method to detect EGFR mutations. Despite its promise, the widespread adoption of ctDNA analysis faces challenges for integration into clinical practice. This review provides a comprehensive synthesis of current knowledge on the clinical utility of EGFR molecular analysis in ctDNA, alongside its relationship with other circulating biomarkers widely implemented in clinical laboratories, such as serum tumor markers (STMs). It delves into the technical considerations, interpretation of results, and other challenges associated with ctDNA analysis, offering valuable insights into its integration into laboratory workflows.