If a person has cancer of the Urethra or uteres near the bladder why would some white cells?

be present in the cytoscopy exam? and why would lots of white cells known as Epithelial cells be high in that person? It shows up all the time now.And just to let you guys know it is not infection, maybe a few yeasts seen but that is it. and there was not red cells detected in the urine the other day. so I just want to know why is cancer cells white inside you with this type of cancer? There is no legion like a bump or lump inside just cancer cells which are white and spreading. why is this?.