What is the role of FGFR3 testing in the diagnosis of bladder cancer?

Updated: Nov 01, 2018
  • Author: Gary David Steinberg, MD, FACS; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Fibroblast growth factor receptor 3 (FGFR3) belongs to a family of tyrosine kinase receptors and is encoded by the FGFR3 gene. Specific point mutations in various domains result in constitutive activation of the receptor and have been found in approximately 50% of urothelial carcinomas. [26] The frequency of these mutations is high in low-grade pTa tumors and low in pT1-4 tumors. The presence of the FGFR3 mutation is a selective marker for favorable disease, with a low recurrence rate and improvement in disease-specific survival. [27, 28, 29]

Predictive Biosciences (Lexington, Mass) developed a urine-based FGFR3 assay using ultradeep amplicon sequencing, allowing a high clinical sensitivity of 55.8% and specificity of 100%, similar to that of tissue. [30] They have implemented the use of this assay in a multianalyte diagnostic assay, CertNDx, used for the evaluation of hematuria and monitoring bladder cancer recurrence. For the diagnosis of urothelial carcinoma, they analyze urine for the presence of mutant FGFR3, quantified matrix metalloproteinase 2 (MMP-2), and hypermethylation of TWIST1 and NID2. This allows for the presence of 2 biomarker cutoff values. The presence of FGFR3 provides a high positive predictive value of 95.2%, while the lack of all 4 biomarkers provides a negative predictive value of 98.2%. [31] Furthermore, unlike other assays, this is not affected by the degree of hematuria or presence of other urinary tract diseases. [32]

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