What Is It?
The kidneys are two bean shaped organs that below the rib cage in the back, to the right and left of the spine. They serve as the body’s filters to cleanse the blood of waste products, excess water and salt. They also produce a hormone called renin, which monitors blood pressure, and a hormone called erythropoietin, which regulates the production of red blood cells.
In general, kidney cancer is an uncontrolled growth of abnormal kidney cells that ultimately invade and destroy the normal kidney tissue and can spread (metastasize) to other organs. There are three major types of kidney cancer:
- Renal cell carcinoma — Renal cell carcinoma arises from the lining of the small tubes that mass together to make up the kidney. It accounts for 85 percent of all kidney cancers. Although renal cell carcinoma typically develops as a single tumor in only one kidney, both kidneys sometimes are involved. The majority of these tumors are discovered before they spread through the bloodstream or lymph system to other organs. Specific types of renal cell carcinoma are identified according to their appearance under the microscope and according to specific abnormalities in their chromosomes (bits of DNA that carry tumor cell genes). There are three different types of renal cell carcinoma: clear cell tumors (75 percent of all renal cell carcinomas), granular cell tumors and sarcomatoid tumors.
- Transitional cell carcinoma — Transitional cell carcinoma arises from draining kidney tubes as they exit the kidney. It represents 6 percent to 7 percent of all kidney cancers. This cancer has a different microscopic appearance than renal cell carcinoma, and it usually begins in the renal pelvis (the funnel shaped area that connects the ureter to the main portion of the kidney). Studies suggest that transitional cell carcinoma is linked to cigarette smoking.
- Renal sarcoma — Renal sarcoma arises from blood vessels within the kidney or from a mutation of a more common cancer type. It is the rarest form of kidney cancer, and occurs in only 1 percent of cases. When children develop kidney cancer, it is usually a cancer of kidney cells from early development. This childhood tumor is called nephroblastoma, and it is commonly known as Wilms’ tumor.
In the United States, kidney cancer represents 3 percent of all cancers, striking 30,000 people annually and killing 12,000 people a year. Risk factors for cancer in the kidney include cigarette smoking, obesity, prolonged exposure to asbestos or cadmium, family history of kidney cancer, long-term dialysis treatment, heavy consumption of fried or sauteed meats, being between age 50 and 70, and tuberous sclerosis, a disease characterized by multiple bumps on the skin caused by small tumors of the blood vessels.
Most kidney cancers grow without causing any pain or discomfort. When symptoms develop, the classic three are blood in the urine (hematuria), abdominal pain and an abnormal lump or swelling (mass) in the flank or abdomen. Other symptoms can include a constant tired feeling (fatigue), weight loss, unexplained fever, anemia or, in men, a collection of enlarged veins in the scrotum called a varicocele.
Many people with kidney cancer do not have any symptoms. In these people, a kidney tumor sometimes is identified by accident when X-rays of the abdomen are taken to evaluate a different health problem.
Your doctor will take a thorough medical history to check for risk factors and symptoms. You also will be asked whether you smoke (how much, how long), whether you’ve been exposed to asbestos or cadmium at work, and whether you have a family history of kidney disease. In addition, your weight, age and any other diseases (such as tuberous sclerosis) will be taken into account.
During your physical examination, the doctor will feel your flank and abdomen for any abnormal masses. To confirm the diagnosis of kidney cancer and to determine how far the cancer has spread, the following tests may be done:
- Intravenous pyelography — In this X-ray test, a dye is injected into a vein. The dye collects in the kidneys and is excreted in the urine, providing an outline of the urine producing path. This test can help identify kidney cancer and outline areas of cancer related kidney damage.
- Ultrasonography — This test uses sound waves to help establish whether a kidney mass is a noncancerous (benign) fluid filled cyst or a potentially cancerous solid tumor.
- Computed tomography (CT) scan of the abdomen and pelvis — In a CT scan, a modified X-ray beam produces body images at different angles, offering a cross sectional look at the inside of the kidneys, abdominal organs and pelvic organs.
- Chest X-ray — This is used to determine whether kidney cancer has spread to the lungs or to the bones of the chest area.
- Urinalysis — About 50 percent of people with renal call carcinoma have hematuria (blood in the urine). Chemical testing and microscopic examination of the urine can detect small amounts of blood that are not visible to the eye.
- Magnetic resonance imaging (MRI) — In this test, large magnets and radio waves are used to provide cross sectional, computer generated pictures of the kidney and nearby organs. This test is especially useful in people who are allergic to the dye used in intravenous pyelography. An MRI also can check to see if cancer has spread to major abdominal blood vessels.
- Bone scan — In this test, small and safe levels of radioactive materials help identify where cancer has spread to the bones.
- Venography — In this X-ray test, a dye is injected into the inferior vena cava to determine if the cancer has spread into the renal vein and vena cava.
- Arteriography — In this X-ray test, a dye is injected into an artery leading to the kidney to outline the kidney’s blood vessels.
- Blood tests — A complete blood count (CBC) can show too few red blood cells (anemia) or too many red blood cells (polycythemia), either of which can be seen in people with kidney cancer. Blood chemistry studies also can check for high levels of liver enzymes or calcium, which sometimes accompany kidney cancer.
- Fine needle aspiration — In rare cases, a thin sterile needle is used to remove a sample of fluid and cells from the kidney tumor. This sample is examined under a microscope for evidence of cancer.
In general, most kidney cancers will continue to grow and spread until treatment is provided. However, about 10 percent of people with metastatic renal cell carcinoma experience a short period (about 12 months) when their cancer stabilizes and does not progress. Doctors also have documented very rare cases in which renal cell carcinoma has disappeared spontaneously.
Because the cause of most kidney cancers is unknown, it is not possible to prevent all of them. However, because 25 percent to 30 percent of renal cell carcinoma is linked to cigarette smoking, you may be able to reduce your risk of renal cell carcinoma by avoiding tobacco. In the workplace, avoid exposure to asbestos and cadmium. To identify early kidney cancer in people receiving dialysis, doctors recommend periodic kidney X-rays.
Treatment is determined by the type of cancer and how far it has spread (its stage), as well as by the person’s age, general health and personal preferences. The primary types of treatment for kidney cancers are surgery, chemotherapy, radiation therapy and biologic therapy.
Surgery is considered to be the most important treatment for kidney cancer because the chances of surviving without it are poor. However, it is only used as a way to cure kidney cancer when all of the tumor can be removed. Typically, surgery is not used to treat people with metastatic disease because once the cancer has spread widely, it is impossible to find all of the cancer with surgery and not very helpful to remove the original tumor. People who have cancer that has spread to just one location sometimes are treated as an exception to this rule. The amount of tissue removed depends on the stage and type of kidney cancer. Among the surgical procedures available are the following:
- Radical nephrectomy — The entire kidney, adrenal gland and surrounding lymph nodes and fatty tissue are removed. For some cancers, nephrectomy can be performed using the camera guided surgery known as laparoscopy.
- Partial nephrectomy — Only the portion of the kidney that contains cancer cells is removed. There is a risk that a small amount of cancer may be left behind.
- Arterial embolization — A small tube (catheter) is inserted into an artery in the groin and moved through the blood vessel until it reaches the kidney’s artery. Then material is injected into the artery to block it. This technique can be used before a nephrectomy to stop any kidney bleeding and to kill some of the cancer cells.
- Metastases removal — When kidney cancer has spread to distant sites, these sites are called metastases. Surgically removing metastases can provide temporary relief from pain and other symptoms in the immediate area, but it does not help the person to survive longer.
Radiation therapy relies on high energy radiation to kill cancer cells. This therapy can be used in conjunction with other treatments to ease symptoms. Side effects include nausea, diarrhea, fatigue and sensitivity to sunlight.
Biological therapy, also called immunotherapy, is the most common form of treatment for advanced kidney cancer. It helps the body’s immune defenses fight and destroy cancer cells. This treatment can be given directly in the form of proteins that activate the immune system (cytokines), such as interleukin-2 and interferon-alpha, or in the form of a tumor vaccine that promotes the production of cytokines within cancer cells.
In chemotherapy, anticancer drugs are taken by mouth or delivered through a vein into the bloodstream. Chemotherapy drugs commonly used to treat kidney cancer include vinblastine (Velban), floxuridine (FUDR) and fluorouracil (Adrucil). All have side effects, such as nausea, vomiting and loss of hair. This treatment is used against tumors that are relatively resistant to other treatment.
When To Call A Professional
Contact your doctor immediately if you see blood in your urine, notice an abnormal lump or swelling in your abdomen or have persistent abdominal pain.
The prognosis depends on the stage and type of kidney tumor. In general, if the tumor is diagnosed early, before it breaks through the outer covering of the kidney, the kidney cancer is often curable. If the cancer is removed surgically, and the surrounding areas are free of cancer cells at the time of surgery, the five year survival rate is 50 percent to 70 percent. This survival rate drops to 15 percent to 35 percent in people whose cancer has spread to the lymph nodes and circulatory system. The survival rate for people with distant metastases is 5 percent or less after five years.
Diseases and Conditions Center
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.