The Development of Non-Invasive Diagnostic Tools in Bladder Cancer

Bladder cancer is a common urinary tract cancer with a difficult clinical course. With frequent recurrence, patients with a history of bladder cancer often undergo surveillance that involves invasive cystoscopies and biopsies. Not only is this financially burdensome for patients but it is also mentally and physically intensive. Given this predicament, the field has shifted towards the use of non-invasive urinary tests to detect bladder cancer earlier in the disease course and to avoid unnecessary procedures. The first non-invasive test developed was urine cytology; however, that was found to have a low sensitivity, especially for low-grade lesions. There are many tests that are available that utilize common protein biomarkers to enhance the sensitivity of detection. However, many of these tests lack the specificity seen with cytology. With recent technological and research advancements, there are newer detection systems such as RNA sequencing and microfluidics along with novel bladder cancer biomarkers including mRNAs, methylation patterns and exosomes, which have potential to be used in clinical practice. The aim of this review is to highlight established non-invasive bladder cancer diagnostic tests as well as innovative methodologies that are on the horizon for use in bladder cancer detection.