FGFR3 Testing in Urothelial Carcinoma: An Expert Commentary on Best Practices From Patient Identification to Result...

Metastatic urothelial cancer (mUC) is associated with diverse genomic alterations, including frequent FGFR3 mutations that influence survival outcomes and treatment responses. Erdafitinib, a targeted therapy, has shown improved survival in patients with locally advanced (LA) or mUC harbouring FGFR3 alterations, reinforcing the importance of timely FGFR3 testing.

This article aims to provide practical guidance for step-by-step best practices in FGFR3 testing in mUC from sample acquisition to result reporting.

This narrative review presents practical recommendations for FGFR3 testing in mUC, developed by a multidisciplinary European panel of pathologists, molecular biologists, oncologists, and urologists, based on critical appraisal of current evidence and collective clinical experience.

Patients with LA/mUC should undergo FGFR3 testing at diagnosis, as supported by the current guidelines. Other factors to consider include age, frailty, fitness for treatment, and quality of life. FGFR3 testing should be performed using validated quantitative polymerase chain reaction (PCR) assays or next-generation sequencing (NGS) methods. While liquid biopsy analysis on circulating tumour deoxyribonucleic acid (ctDNA) via PCR and NGS may offer a complementary approach to tissue testing, further research is needed to determine its value in detecting FGFR3 alterations in mUC. The molecular laboratory report should contain details of all detected genetic alterations by the European Society for Medical Oncology Scale for Clinical Actionability of molecular Targets tier to indicate potential actionability.

Early FGFR3 testing at diagnosis in patients with LA/mUC is clinically essential to ensure timely access to targeted therapies. Multidisciplinary collaboration is key to integrating molecular testing into patient care, supporting effective and personalised disease management.