Lung Cancer Biomarker Testing: IHC, Tissue Genomics, Digital Pathology, and ctDNA.

Testing for predictive biomarkers in lung cancer has evolved to integrate immunohistochemistry, tissue-based next-generation sequencing (NGS), and liquid biopsy. Tissue-based NGS remains the foundation for comprehensive genomic profiling, enabling detection of actionable mutations and guiding personalized therapies. RNA-based assays complement DNA testing by improving fusion detection. Liquid biopsy using circulating tumor DNA (ctDNA) offers a minimally invasive alternative for genotyping, monitoring treatment response, and assessing minimal residual disease, though sensitivity challenges persist in early-stage disease. Immunohistochemistry for PD-L1 and emerging antibody-drug conjugate targets further expands therapeutic options. Workflow optimization, including molecular tumor boards, reflex testing, and rapid assays, is critical to reduce turnaround times. Lastly, advances in digital pathology and AI promise novel biomarker discovery and integration into clinical practice, ensuring accurate interpretation and personalized treatment strategies in the rapidly evolving field of lung cancer personalized oncology.