Kidney cancer, or more properly renal cancer, is any cancer that originates in the cells of the kidneys. The two most common in adults are renal cell carcinoma (accounting for about 80% of all kidney cancer) and transitional cell carcinoma (accounting for about 10%). In children under the age of 5, Wilms' tumors are the most common, but those are rare in those older than 5. In addition, there are several other cancers that can originate in the kidneys, but usually manifest elsewhere, such as teratoma. In the United States, there are about 65,000 newly diagnosed cases every year and about 13,000 deaths.
Prognosis depends on how far the cancer has spread. If if is confined to the kidney, the five year survival rate is about 90%. However, if the cancer has mestastisized, the rate drops to about 10%.
The most common symptoms of kidney cancer are masses in the abdomen and blood in the urine. The latter symptom indicates that immediate medical attention is necessary, although it is not an emergency situation.
Kidney cancer has several risk factors including smoking, frequent use of NSAIDs, obesity, genetics, a family history of the condition, kidney disease (particularly where dialysis is required), hepatitis C and a prior cancer of the testicles in males or the ovaries in females.