Bladder cancer is a condition where cells in the bladder grow abnormally and without control, potentially forming a tumor. It is a common cancer, ranking as the tenth most frequent type globally, and its incidence is increasing with an aging population. Detecting bladder cancer early is highly beneficial, as it significantly improves treatment options and the likelihood of successful outcomes. Urine tests play a role in this early detection process by examining substances and cells shed from the urinary tract.
Why Urine Tests are Used for Bladder Cancer
Urine tests assist healthcare providers in several ways. When a patient shows symptoms such as blood in the urine (hematuria), these tests help determine if bladder cancer is present. Hematuria is a common early sign of bladder cancer, though it can also stem from other conditions like kidney stones or infections.
For individuals previously treated for bladder cancer, urine tests monitor for recurrence, which is important as bladder cancer has a notable chance of returning. While less common for general screening, urine tests are also being investigated for screening high-risk populations, such as heavy smokers or those with certain occupational exposures.
Different Types of Urine Tests
Several types of urine tests are employed to help detect bladder cancer, each looking for different indicators within the urine sample. These tests examine cells, proteins, or genetic material that may be shed by cancerous bladder cells.
Urine Cytology
Urine cytology involves the microscopic examination of cells collected from a urine sample to identify any abnormal or cancerous cells. This test operates on the principle that rapidly multiplying cancer cells may shed into the urine. While generally effective in identifying high-grade tumors, with a reported sensitivity of around 48% to 84% for these aggressive cancers, its sensitivity for low-grade tumors is considerably lower, sometimes as low as 10% to 16%.
Urine Marker Tests
Urine marker tests, also known as biomarker tests, detect specific substances released by bladder cancer cells into the urine. These biomarkers can include various proteins and genetic materials like DNA and RNA.
NMP22 BladderChek® Test
The NMP22 BladderChek® Test is an immunoassay that detects nuclear matrix protein 22 (NMP22) in urine. Bladder cancer cells often release higher levels of NMP22 compared to normal cells. This test can provide results within approximately 30 minutes. Studies indicate the NMP22 BladderChek test has a pooled sensitivity of about 56% and a specificity of 88% for detecting bladder cancer, with diagnostic performance improving for higher-grade and higher-stage tumors.
UroVysion™ FISH
The UroVysion™ FISH (Fluorescence In Situ Hybridization) test identifies chromosomal abnormalities often present in bladder cancer cells. It uses fluorescently labeled DNA probes to detect specific chromosomal changes. UroVysion has been approved for detecting recurrent bladder cancer and for initial diagnosis in patients with hematuria, showing higher sensitivity than urine cytology for various stages and grades of bladder cancer, though cytology may have higher specificity.
Cxbladder
Cxbladder is a suite of molecular diagnostic tests that analyze the expression of multiple biomarker genes in urine. These tests are used to help rule out urothelial bladder cancer in patients with blood in urine and to monitor for recurrence in those treated for non-muscle invasive bladder cancer. Cxbladder aims to reduce the need for invasive procedures, such as cystoscopy.
Emerging DNA/RNA Tests
Emerging tests analyze tumor-derived DNA (utDNA) and RNA. These tests can detect genetic mutations, DNA methylation patterns, and RNA biomarkers shed by cancer cells into the urine. For example, some approaches combine the detection of TERT mutations with FGFR3 evaluations to enhance diagnostic accuracy, potentially achieving sensitivities around 68.9% to 78.6% and specificities up to 96% to 100% when combined with urine cytology. These advanced technologies aim to improve early detection, diagnosis, and surveillance of bladder cancer.
Understanding Your Test Results
Interpreting urine test results for bladder cancer involves understanding what different outcomes might signify. Results generally indicate whether abnormal, pre-cancerous, or cancerous cells are present.
A “negative for high-grade urothelial carcinoma” result means no cancer cells or highly abnormal cells were found. An “atypical urothelial cells” result suggests some abnormalities were observed, but these cells were not definitively cancerous. Such indeterminate findings usually warrant further investigation. If the report indicates “suspicious for high-grade urothelial carcinoma” or “positive for high-grade urothelial carcinoma,” it means abnormal or cancer cells were identified. Urine tests are screening or diagnostic aids and do not provide a definitive diagnosis on their own.
Limitations and Next Steps
Urine tests for bladder cancer, while valuable, have certain limitations regarding their accuracy. Sensitivity refers to a test’s ability to correctly identify individuals with cancer, while specificity indicates its ability to correctly identify those without cancer. Urine tests are screening or diagnostic aids and do not provide a definitive diagnosis on their own.
A negative urine test result does not always rule out bladder cancer, especially if symptoms persist or there is a high suspicion of the disease. Even with a negative test, healthcare providers may recommend further diagnostic procedures to ensure an accurate diagnosis. If a urine test is positive or highly suspicious, the typical next steps often involve a cystoscopy, a procedure where a thin camera is inserted into the bladder to visualize its lining. During a cystoscopy, a biopsy (tissue sample) may be taken for microscopic examination to confirm the diagnosis and determine the cancer’s characteristics. Additional imaging tests, such as CT scans or MRIs, may also be performed to assess the extent of the cancer if it is confirmed.