Kidney cancer is cancer that begins in the kidneys your kidneys are two bean shaped organs each about the size of your fist theyre 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. Learn about the causes risk factors and prevention of kidney cancer and what you might be able to do to help lower your risk from the american cancer society early detection diagnosis and staging know the signs and symptoms of kidney cancer find out how kidney cancer is tested for diagnosed and staged from the american cancer society. What is kidney cancer kidney cancer also called renal cancer is a disease in which kidney cells become malignant cancerous and grow out of control forming a tumor almost all kidney. Kidney cancer is the abnormal growth of cells in kidney tissue in time these cells form a mass called a tumor cancer begins when something triggers a change in the cells and they divide out of control a cancerous or malignant tumor can spread metastasize to other tissues and vital organs