The present disclosure provides compositions comprising a food product, non-pathogenic microorganism, kits, methods of diagnosing a tumor in a subject, methods of quantifying the number of cancer cells in a cell sample, and methods of detecting a cancer cell, cancer tissue, or cell associated with a hyperproliferative disorder. In some embodiments, the method comprises a step of detecting the presence or absence of a modified substrate or portion thereof in urine of an animal without an instrument and solely by visual inspection of the urine.