Optimization of nonmuscle invasive bladder cancer recurrence detection using a urine based FGFR3 mutation assay.

PURPOSE: FGFR3 mutations occur in 70% of nonmuscle invasive bladder tumors. Although urine based FGFR3 mutation analysis can detect recurrence, its sensitivity may be limited if samples have few or no tumor cells. We determined whether test sensitivity depends on tumor size and the time point of urine collection, and how to increase sensitivity. MATERIALS AND METHODS: A total of 440 urine samples from 18 patients with a suspicious bladder lesion at cystoscopy were collected during 6 days before surgery. Eight patients (300 samples) had an FGFR3 mutant tumor, including 4 each with a tumor greater than 3 and less than 1.5 cm. Polymerase chain reaction based FGFR3 analysis was done on all tumors and urine samples. RESULTS: FGFR3 mutations were detected in 257 of the 300 urine samples (86%) from patients with an FGFR3 mutant tumor. Assay sensitivity was 100% for tumors greater than 3 cm and 75% for tumors less than 1.5 cm. It increased to 100% in patients with a less than 1.5 cm tumor when samples were pooled during 24 hours. Sensitivity was not influenced by the time of urine collection. All urine samples from patients with an FGFR3 wild-type tumor were negative for FGFR3 mutation. CONCLUSIONS: The sensitivity of tumor detection increased with tumor size. FGFR3 assay sensitivity depends on the number of shed tumor cells and improves by increasing urine volume. These findings suggest that there is an upper limit to the sensitivity of the FGFR3 assay when 1 urine sample is analyzed. This may also apply to other DNA or RNA based assays.

In-depth investigation of the molecular pathogenesis of bladder cancer in a unique 26-year old patient with extensive multifocal disease: a case report.

BACKGROUND: The molecular characteristics and the clinical disease course of bladder cancer (BC) in young patients remain largely unresolved. All patients are monitored according to an intensive surveillance protocol and we aim to gain more insight into the molecular pathways of bladder tumors in young patients that could ultimately contribute to patient stratification, improve patient quality of life and reduce associated costs. We also determined whether a biomarker-based surveillance could be feasible. CASE PRESENTATION: We report a unique case of a 26-year-old Caucasian male with recurrent non-muscle invasive bladder tumors occurring at a high frequency and analyzed multiple tumors (maximal pTaG2) and urine samples of this patient. Analysis included FGFR3 mutation detection, FGFR3 and TP53 immunohistochemistry, mircosatellite analysis of markers on chromosomes 8, 9, 10, 11 and 17 and a genome wide single nucleotide polymorphism-array (SNP). All analyzed tumors contained a mutation in FGFR3 and were associated with FGFR3 overexpression. None of the tumors showed overexpression of TP53. We found a deletion on chromosome 9 in the primary tumor and this was confirmed by the SNP-array that showed regions of loss on chromosome 9. Detection of all recurrences was possible by urinary FGFR3 mutation analysis. CONCLUSIONS: Our findings would suggest that the BC disease course is determined by not only a patient's age, but also by the molecular characteristics of a tumor. This young patient contained typical genetic changes found in tumors of older patients and implies a clinical disease course comparable to older patients. We demonstrate that FGFR3 mutation analysis on voided urine is a simple non-invasive method and could serve as a feasible follow-up approach for this young patient presenting with an FGFR3 mutant tumor.