Urothelial carcinoma is the seventh most common cancer worldwide and approximately 70% are non-muscle invasive tumours. Unfortunately, up to 70% of patients with a history of non-muscle invasive bladder cancer will have recurrence after initial treatment and approximately 10% to 30% of these tumours will progress to muscle invasive disease, which significantly increases the risk of cancer-related death.
Traditionally, urine cytology and cystoscopy are considered as the gold standard for diagnosis and surveillance of urothelial carcinoma, however both have limitations. First, although the urine cytology is excellent for detecting high-grade urothelial carcinoma (sensitivity and specificity > 75%), it has a low sensitivity (20–60%) for detecting low- grade tumours. Second, the cystoscopy is an invasive procedure and has limited usefulness in detecting flat and inaccessible lesions.
The low sensitivity of urine cytology and the invasiveness of cystoscopy have increased the demand for more sensitive and non-invasive tests for detection of urothelial carcinoma. This has led to the development fluorescence in situ hybridization (FISH) that have a higher sensitivity (73–92%) and specificity (89–96%) for detection of urothelial carcinoma. This molecular test employs DNA probes to identify the most common urothelial carcinoma related chromosomal abnormalities in urine such as aneuploidy for chromosomes 3, 7, 17, and loss of the 9p21 locus in malignant urothelial cells that are shed in the urine of persons with urothelial carcinoma.
Food and Drug Administration initially approved its use as a surveillance tool for patients with a history of urothelial carcinoma. However, this was later extended to include its use as a screening tool in patients with hematuria and risk factors for urothelial carcinoma and it can be applied to formalin fixe paraffin-embedded (FFPE) tissue.
Benjamin et.al have demonstrated that the percentage of abnormal cells detected by FISH in urine specimens is associated with bladder cancer recurrence and progression to muscle-invasive cancer. These data can help urologists identify patients that are at higher risk for bladder cancer recurrence and progression to muscle-invasive disease.
The test is carried out within 7 working days from reception of the sample.