Renal Cell Carcinoma is the most common type of kidney cancer. It begins in the lining of the renal tubules in the kidney. Most of those affected are between the ages of 50 and 70. It can start as a single tumor or several tumors in a kidney, or can be found in both kidneys. Other terms for this cancer are hypernephroma, renal cell adenocarcinoma, or renal cell cancer. The exact cause of renal cell carcinoma is not known, but smoking and misuse of certain pain medicines can affect the risk of renal cell cancer in addition to having certain genetic conditions.