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.
Types of Kidney Cancer
Several types of cancer can start in the kidney.
- Renal cell carcinoma is the most common type of kidney cancer in adults. It forms in the lining of very small tubes in the kidney that filter the blood and remove waste products.
- Transitional cell carcinoma forms in the center of the kidney where urine collects. More than 64,000 new cases are diagnosed annually in the U.S. according to the National Cancer Institute.
- Wilms’ Tumor is the most common type of childhood kidney cancer. It requires a different approach to treatment than adult kidney cancers.
Kidney Cancer Symptoms
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:
- Blood in the urine, even microscopic
- Persistent pain in the side
- A lump in the side of the abdomen
- Weight loss
- Feeling very tired or a general feeling of being unwell
Metastatic Kidney Cancer
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:
- Through tissue: Cancer invades the surrounding normal tissue.
- Through the lymph system: Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood: Cancer invades the veins and capillaries and travels through the blood to other places in the body.
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.