Kidney cancer is a type of cancer that starts in the cells in the kidney. The two most common types of kidney cancer are renal cell carcinoma (RCC) and urothelial cell carcinoma (UCC) of the renal pelvis. These names reflect the type of cell from which the cancer developed.

The different types of kidney cancer (such as RCC and UCC) develop in different ways, meaning that the diseases have different outlooks (or prognosis), and need to be staged and treated in different ways. RCC is responsible for approximately 80% of primary renal cancers, and UCC accounts the majority of the remainder.