Renal cell carcinoma, the predominant type of kidney cancer, is among the 10 most common cancers and accounts for 2% to 3% of all human cancers. The American Cancer Society estimated approximately 57,760 new cases of kidney cancer in the United States in 2009 and approximately 12,980 deaths. Renal cell carcinoma represents 80% to 90% of kidney cancers in adults. For reasons that are not completely understood, the incidence of renal cell carcinoma is increasing worldwide. Approximately 25% to 30% of patients with renal cell carcinoma present with metastatic disease. Metastatic renal cell carcinoma is resistant to both conventional chemotherapy and radiotherapy, and the prognosis is poor, with an overall 5-year survival rate of approximately 10%.