Bladder cancer is one of the most common forms of cancer in North America. Most often, bladder cancer presents as superficial disease, which is treatable through surgical resection, but is also associated with recurrence rates of up to 70%. Thus, patients must be monitored at regular intervals following resection of the tumor to assess for recurrence. This monitoring is done by cystoscopy, which requires a scope to be inserted into the urethra and into the bladder to visually inspect the bladder wall, and is associated with significant patient discomfort, poor compliance to the recommended screening schedule, and high screening costs as cystoscopy must be performed by a physician. Indeed, the cost of screening and surgical interventions makes bladder cancer the most expensive cancer to treat on a per patient basis. Finally, small masses are likely to be missed by visual inspection, resulting in sub-optimal assessment of recurrence. The bladder cancer community has recognized the problems with cystoscopy as the primary screening technique, resulting in a number of attempts to develop urine based assays to more accurately assess the presence of recurrent disease. These assays have looked for the presence of cancer cells or specific proteins associated with cancer. Unfortunately, most of these tests lack specificity, as they measure processes that may be present in other non-cancer conditions such as infection or kidney stone disease, or lack sensitivity, as they measure events that are present only in a subset of bladder cancer patients, usually high-grade disease. As a result, none of the urine based tests currently available are recommended by the American Urological Association as a primary screening tool. We propose to take advantage of recent technological advances and our understanding of the molecular processes involved in bladder cancer to develop a comprehensive screening panel that assays the urine of patients. This technique is non-invasive, and we estimate that we will be able to detect more 90-95% of all bladder cancer patients, giving us high sensitivity to detect recurrent disease, including patients with low grade disease who are missed by current screening techniques. We have performed preliminary tests on patient samples and accurately detected tumors in greater than 90% of such patients. We have also performed testing in normal controls, and none have tested positive for the presence of cancer. Thus, we believe that the test will also have high specificity. Our current proposal aims to build upon our preliminary data by expanding the panel of biomarkers that we assay for even greater coverage, and to investigate technical enhancements to improve the sensitivity. This approach will lead to the development of a non-invasive screening assay that will have excellent sensitivity and specificity at a lower price point than current screening techniques. Thus, the successful development of our assay will improve patient outcomes while reducing the cost burden on the health care system.