The kidneys are a pair of organs on either side of the spine in the upper abdomen. Each kidney is slightly larger than the size of a fist. Attached to the top of each kidney is an adrenal gland. A mass of fatty tissue and an outer layer of fibrous tissue (Gerota's fascia) enclose the kidneys and adrenal glands.
The kidneys are part of the urinary tract. They make urine by removing wastes and extra water from the blood. Urine collects in a hollow space (renal pelvis) in the middle of each kidney. It passes from the renal pelvis into the bladder through a tube called a ureter. Urine leaves the body through another tube (the urethra). The kidneys also make substances that help control blood pressure and the production of red blood cells. The function of the nearby adrenal gland is to make certain hormones, including adrenaline.
Several types of cancer can start in the kidney.
Early kidney cancer doesn’t reveal itself with symptoms, so often the disease is detected by chance. These signs do not always mean cancer, however patients with these symptoms should see a doctor for further examination:
When kidney cancer spreads beyond the kidney, it is considered metastatic disease. At that point, the cancer becomes more difficult to treat. The three ways that kidney cancer spreads in the body are:
When kidney cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if kidney cancer spreads to the lung, the cancer cells in the lung are actually kidney cancer cells. The disease is metastatic kidney cancer, not lung cancer.