Kidney cancer is cancer that begins in the kidneys. Your kidneys are two bean-shaped organs, each about the size of your fist. They're located behind your abdominal organs, with one kidney on each side of your spine.
In adults, renal cell carcinoma is the most common type of kidney cancer. Other less common types of kidney cancer can occur. Young children are more likely to develop a kind of kidney cancer called Wilms' tumor.
The incidence of kidney cancer seems to be increasing. One reason for this may be the fact that imaging techniques such as computerized tomography (CT) scans are being used more often. These tests may lead to the accidental discovery of more kidney cancers. Kidney cancer is often discovered at an early stage, when the cancer is small and confined to the kidney.