kidney cancer

Your kidneys are two bean-shaped organs, each about the size of your fist. They're located behind your abdomen, one on each side of your spine. Like other major organs in the body, the kidneys can sometimes develop cancer. In adults, the most common type of kidney cancer is renal cell carcinoma (renal adenocarcinoma), which begins in the cells that line the small tubes within your kidneys. Children are more likely to develop a kind of kidney cancer called Wilms' tumor.

Kidney cancer seldom causes problems in its early stages. But as a tumor grows, you may notice blood in your urine or experience unintentional weight loss or back pain that doesn't go away. Kidney cancer cells may also spread (metastasize) outside your kidneys to nearby organs as well as to more distant sites in the body. Yet if kidney cancer is detected and treated early, the chances for a full recovery are good.

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.