Renal Cell (Kidney) Cancer
The most common type of kidney cancer is renal cell carcinoma (RCC), which arises in the renal parenchyma (the part of the kidney that makes urine). RCC accounts for more than 90 percent of kidney cancers. Nearly three-quarters of RCCs are classified as clear cell carcinomas because of their pale appearance when examined under a microscope. The other major type of RCC is called papillary carcinoma. In addition to RCC, other cancers that occur in the kidney are transitional cell carcinomas of the renal pelvis (the part of the kidney where urine collects and drains to the ureters and the bladder), sarcomas, and Wilms tumors, a rare type that occurs almost exclusively in children. Cigarette smoking, obesity, and hypertension appear to contribute to the risk of RCC. In addition, mutations in more than 15 genes have been associated with RCC, both in the inherited and sporadic forms, but they provide only a partial picture of the complex processes of this disease. Kidney cancer incidence has increased steadily over the past several decades, a rise attributed in part to increased detection of early-stage disease. Moreover, kidney cancer mortality rates have improved little in the past 20 years. This year in the United States, it is estimated that more than 64,000 people will be diagnosed with kidney cancer and about 13,000 will die from it. Greater understanding, gleaned from laboratory research on the molecular underpinnings of RCC, has yielded new strategies for its treatment, including the first generation of molecularly targeted therapies, many of which deplete tumor cells of nutrients and oxygen by blocking the growth of blood vessels.