The “grade” of the cancer is an estimate of the speed of tumor growth a suggested by cell features seen under a microscope. The type of cancer cells for bladder cancer is almost always transitional cell and the cancer cells are classified into three grades that correspond to well, moderately and poorly differentiated cells. Your doctor should be able to tell you whether the cancer cells are high grade or low grade based upon the cellular features of the cancer cells under a microscope. A “low grade” tumor is indolent and slow growing while a “high grade” tumor is aggressive and fast growing.