Kidney cancer is a disease of the kidneys, the reddish-brown curving organs about the size of a small fist, located above the waist to either side of the spine. They are closer to the back of the body than to the front. In kidney cancer, cells grow unregulated by the signals that normally regulate cell growth and death, and form tumors.

Kidneys filter blood and remove impurities, excess minerals and salts, and surplus water. Every day, they process about 200 quarts of blood to generate two quarts of urine. These organs also produce hormones to help control blood pressure, red blood cell production, and other functions. Although people have two kidneys, each works independently. The human body can function with less than one complete kidney. With dialysis, a mechanized filtering process, it is possible to live without kidneys.

There are several types of kidney cancers:

Renal cell carcinomas comprise about 85% of kidney cancers. This cancer develops within the kidney's microscopic filtering systems, in the lining of tiny tubules.

Transitional cell carcinoma begins in the area of the kidney where urine collects before being funneled to the bladder. This type of kidney cancer is similar to bladder cancer and is treated like bladder cancer.

Wilm's tumor, found most often in children, is also treated differently from adult kidney cancer.

Knowing which kind of cell a tumor is composed of helps doctors plan treatment. In kidney cancer, there are four types, of which two are notable: "clear cell" is the kind found in 80% of kidney cancer, and "sarcomatoid" is the most aggressive type.

Surgery to remove a kidney tumor, or the kidney itself, provides a reasonable chance of cure if the cancer has not spread beyond the confines of the organ. If it has metastasized, kidney cancer is difficult to treat with traditional therapies. Since one percent of all kidney cancers spontaneously shrink or disappear, scientists have focused on the body's immune system as a useful tool to treat advanced kidney cancer.

Kidney Cancer: Who's at Risk?

Kidney cancer develops most often in people over 40, but no one knows the exact causes of this disease. Doctors can seldom explain why one person develops kidney cancer and another does not. However, it is clear that kidney cancer is not contagious. No one can "catch" the disease from another person.

Research has shown that people with certain risk factors are more likely than others to develop kidney cancer. A risk factor is anything that increases a person's chance of developing a disease.

Studies have found the following risk factors for kidney cancer:

* Smoking: Cigarette smoking is a major risk factor. Cigarette smokers are twice as likely as nonsmokers to develop kidney cancer. Cigar smoking also may increase the risk of this disease.

* Obesity: People who are obese have an increased risk of kidney cancer.

* High blood pressure: High blood pressure increases the risk of kidney cancer.

* Long-term dialysis: Dialysis is a treatment for people whose kidneys do not work well. It removes wastes from the blood. Being on dialysis for many years is a risk factor for kidney cancer.

* Von Hippel-Lindau (VHL) syndrome: VHL is a rare disease that runs in some families. It is caused by changes in the VHL gene. An abnormal VHL gene increases the risk of kidney cancer. It also can cause cysts or tumors in the eyes, brain, and other parts of the body. Family members of those with this syndrome can have a test to check for the abnormal VHL gene. For people with the abnormal VHL gene, doctors may suggest ways to improve the detection of kidney cancer and other diseases before symptoms develop.

* Occupation: Some people have a higher risk of getting kidney cancer because they come in contact with certain chemicals or substances in their workplace. Coke oven workers in the iron and steel industry are at risk. Workers exposed to asbestos or cadmium also may be at risk.

* Gender: Males are more likely than females to be diagnosed with kidney cancer. Each year in the United States, about 20,000 men and 12,000 women learn they have kidney cancer.

Most people who have these risk factors do not get kidney cancer. On the other hand, most people who do get the disease have no known risk factors. People who think they may be at risk should discuss this concern with their doctor. The doctor may be able to suggest ways to reduce the risk and can plan an appropriate schedule for checkups.

Possible signs of renal cell cancer include blood in the urine and a lump in the abdomen.

These and other symptoms may be caused by renal cell cancer or by other conditions. There may be no symptoms in the early stages. Symptoms may appear as the tumor grows. A doctor should be consulted if any of the following problems occur:

* Blood in the urine.

* A lump in the abdomen.

* A pain in the side that doesn't go away.

* Loss of appetite.

* Weight loss for no known reason.

* Anemia.

What are the symptoms of kidney cancer?

The most common symptom of kidney cancer is blood in the urine. In some cases, a person can actually see the blood. It may be present one day and not the next. Traces of blood may also be found in urinalysis, a urine test done as part of a regular medical checkup.

Another symptom of kidney cancer is a lump or mass that can be felt in the kidney area. The tumor may cause a dull ache or pain in the back or side. Less often, signs of a kidney tumor include high blood pressure or an abnormal number of red blood cells.

Symptoms may develop suddenly. However, as with other types of cancer, kidney cancer can cause a general feeling of poor health. People with this disease may feel tired, lose their appetite, and lose weight. Some have a fever that comes and goes. These symptoms may be caused by cancer or by other, less serious problems such as an infection or a fluid-filled cyst. A doctor is consulted for a definite diagnosis.

Tests that examine the abdomen and kidneys are used to detect (find) and diagnose renal cell cancer.

The following tests and procedures may be used:

* Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.

* Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that produces it.

* Urinalysis: A test to check the color of urine and its contents, such as sugar, protein, blood, and bacteria.

* Liver function test: A procedure in which a sample of blood is checked to measure the amounts of enzymes released into it by the liver. An abnormal amount of an enzyme can be a sign that cancer has spread to the liver. Certain conditions that are not cancer may also increase liver enzyme levels.

* Intravenous pyelogram (IVP): A series of x-rays of the kidneys, ureters, and bladder to find out if cancer is present in these organs. A contrast dye is injected into a vein. As the contrast dye moves through the kidneys, ureters, and bladder, x-rays are taken to see if there are any blockages.

* Ultrasound: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.

* CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.

* MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).

* Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. A thin needle is inserted into the tumor and a sample of tissue is withdrawn. A pathologist then views the tissue under a microscope to check for cancer cells.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

* The stage of the disease.

* The patient's age and general health.

As we well know, there are many kinds of cancer; unfortunately they all come about because of the out-of-control growth of abnormal cells.