There are an estimated 72,820 diagnosis of kidney cancer made in the United States each year, resulting in nearly 15,000 deaths annually. Kidney cancer is complex in that it may occur in varying locations in the kidney and may also involve a range of cell types. Renal cell carcinoma, occurring in the blood-filtering renal tubules, makes up about 85% of kidney cancer diagnoses. Urothelial carcinoma is less common, but still accounts for around 15% of cases. This cancer type originates in an area called the renal pelvis, through which urine passes on its way to the bladder. Correctly identifying the cell type which forms the tumor can help determine the best course of treatment. There may be as many as 20 different types of kidney cells, but clear cells form the majority of kidney cancers.