Abstract
Biomarkers have transformed cancer care by linking molecular insights to personalized treatment strategies. This review first surveys the spectrum of detection modalities, including tissue genomics and histopathology; liquid biopsies such as circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and extracellular vesicles; imaging and radiomics; and multi-omic approaches spanning epigenomics, transcriptomics, proteomics, metabolomics, and microbiomics. We then critically appraise the translational challenges that hinder clinical implementation, assay standardization, data integration, analytical and clinical validation, regulatory pathways, and cost-effectiveness. Finally, we explore emerging solutions, including artificial intelligence (AI)-driven multi-modal phenotyping, adaptive trial designs, and point-of-care assays, and outline future directions for expanding access and equitable adoption. By emphasizing the central role of biomarkers in guiding targeted and immune-based therapies, we underscore their potential to overcome tumor heterogeneity, preempt resistance, and ultimately improve patient outcomes.