Definition

Kidney cancer is a disease in which cancer cells grow in the kidneys. The kidneys are two bean-shaped organs, located just above the waist, on each side of the spine. Their main function is to filter the blood and produce urine by which the body rids itself of waste products and excess water.

Cancer occurs when cells in the body (in this case kidney cells) divide without control or order. Normally, cells divide in a regulated manner. If cells keep dividing uncontrollably when new cells are not needed, a mass of tissue forms, called a growth or tumor. The term cancer refers to malignant tumors, which can invade nearby tissue and spread to other parts of the body. A benign tumor does not invade or spread.

There are two main types of kidney cancer: Wilms tumor, which occurs predominantly in children, and renal cell carcinoma in adults. The cells that line the ureter may also give rise to transitional cell cancer, and the connective tissues of the kidney may produce sarcomas, which are rare.

Cancer Cell Growth

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Causes

The cause of kidney cancer is unknown.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors for kidney cancer include:

• Smoking
• Family history of certain hereditary forms of kidney cancer
• Age: 50 years or older
• Sex: male
• Certain occupational exposures (like asbestos and aniline) and tanning products
• Exposure to some toxins, such as astrolachia (an herb common in some Chinese herbal preparations)
• Balkan nephritis
• Chronic renal stones
• Phenacetin abuse
• Tuberous sclerosis—a hereditary condition that causes tumors to grow in many different organs, including angiomyolipomas of the kidney, a benign tumor
• Dialysis treatment
• Von Hippel Lindau syndrome—a syndrome associated with many types of cancer

Symptoms

Symptoms may include:

• Blood in the urine
• Unexplained lower back pain or new pain elsewhere
• Shortness of breath or cough
• Lump in the belly
• Elevated blood pressure
• Unplanned, significant weight loss
• Unexplained fever
• Swelling of ankles, legs, and/or abdomen

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam.

Tests may include:

• Blood and urine tests—to check kidney function or find substances that indicate kidney cancer may be present
• Bone scan—for this test, you receive a special radioactive material that specifically lights up bones that are undergoing an active process, such as tumor growth. Kidney cancer likes to spread to the bones. This test is often performed to ensure the bones are not involved by the cancer.
• Chest x-rays and abdomen x-rays—tests that use radiation to take pictures of structures inside the body
• IV pyelogram—an x-ray of the kidneys and ureters after injection of contrast dye into the blood
• Renal angiography—an x-ray of arteries that are leading to a possible kidney tumor
• CT scan—a type of x-ray that uses a computer to make pictures of the inside of the kidneys and the surrounding area
• MRI scan—a test that uses magnetic waves to make pictures of the inside of the kidneys and the surrounding area
• Renal ultrasound—a test that uses sound waves to examine the kidneys
• Laparoscopy—a thin, lighted tube inserted through a small incision in the abdomen to look at the kidney
• Cytoscopy—examination of the bladder, ureters, and kidneys via a thin tube inserted through the urethra
• Biopsy—removal of a sample of kidney tissue to test for cancer cells

Treatment

Once kidney cancer is found, staging tests are performed. The purpose of these tests is to find out if the cancer has spread and, if so, to what extent. Treatment depends on the stage.

Surgery is the most important component of any curative approach to kidney cancer. There is some information suggesting immunotherapies (interleukin or interferon) may be of some benefit. Radiation can be used to treat kidney cancer that has spread to the lung, bones, or brain, but it is not considered curative.

Prevention

Measures to prevent kidney cancer are limited:

• Avoid using tobacco products.
• Avoid occupational exposures.

See your doctor at the first sign of possible symptoms, since early detection is the key to cure.