Tumors originating in the mucosa account for more than half of all cancer deaths in the US, therefore, early detection is important. We propose applying a novel technique to real-time diagnosis and assessment of precancerous growth and early cancer of the mucosa, by measuring its fluorescence independently of the much stronger submucosal fluorescence. Fluorescence and scattering measurements of the lining of body cavities show promise for early detection of mucosal cancer. Unfortunately, the mucosal signature is obscured thicknesses of 25micro to 150micro, a new confocal arrangement, can substantially reduce submucosal interference. It thus has the potential for reliable and robust early diagnosis, while the lesions are still wholly mucosal and invisible to the unaided eye. After testing in phantoms, we will measure fluorescence and backscattered excitation light in a well-characterized rat model of bladder cancer and correlate the results against histopathology. This will test VPM as the basis of a clinically useful diagnostic tool to be built and tested in Phase 2. We will also compare its performance to existing fluorescence techniques.