Fusion genes in precision oncology: prostate cancer as a diagnostic case study

INTRODUCTION: Fusion genes represent one of the most specific molecular alterations in human cancer and have long served as important diagnostic and therapeutic biomarkers. Advances in next-generation sequencing have driven a rapid expansion in fusion gene discovery. Clinical translation has lagged however, particularly in solid tumors. This review critically examines the role of fusion genes in molecular diagnostics, focusing on opportunities, limitations and clinical implementation. AREAS COVERED: We summarize the biological mechanisms underlying fusion gene formation insofar as they influence diagnostic detection and interpretation. Current technologies for fusion detection in clinical practice are evaluated and major diagnostic pitfalls discussed. Prostate cancer is presented as a diagnostic case study to illustrate both the promise and limitations of fusion gene - based biomarkers. EXPERT OPINION: Despite their biological appeal and tumor specificity, fusion genes remain underutilized in routine diagnostics due to interpretive complexity and limited clinical validation. In our view, fusion genes are most likely to deliver sustained diagnostic value when incorporated into targeted, standardized and context-aware diagnostic frameworks rather than pursued as isolated biomarkers. Over the next five years, fusion gene diagnostics are expected to become more selective, integrative and clinically disciplined, with emphasis shifting from discovery toward validated clinical utility.