No one knows the exact causes of bladder cancer. However, it is clear that this disease is not contagious. No one can "catch" cancer from another person.

People who get bladder cancer are more likely than other people to have certain risk factors. A risk factor is something that increases a person's chance of developing the disease.

Still, most people with known risk factors do not get bladder cancer, and many who do get this disease have none of these factors. Doctors can seldom explain why one person gets this cancer and another does not.

Studies have found the following risk factors for bladder cancer:

• Age. The chance of getting bladder cancer goes up as people get older. People under 40 rarely get this disease.

• Tobacco. The use of tobacco is a major risk factor. Cigarette smokers are two to three times more likely than nonsmokers to get bladder cancer. Pipe and cigar smokers are also at increased risk.

• Occupation. Some workers have a higher risk of getting bladder cancer because of carcinogens in the workplace. Workers in the rubber, chemical, and leather industries are at risk. So are hairdressers, machinists, metal workers, printers, painters, textile workers, and truck drivers.

• Infections. Being infected with certain parasites increases the risk of bladder cancer. These parasites are common in tropical areas but not in the United States.

• Treatment with cyclophosphamide or arsenic. These drugs are used to treat cancer and some other conditions. They raise the risk of bladder cancer.

• Race. Whites get bladder cancer twice as often as African Americans and Hispanics. The lowest rates are among Asians.

• Being a man. Men are two to three times more likely than women to get bladder cancer.

• Family history. People with family members who have bladder cancer are more likely to get the disease. Researchers are studying changes in certain genes that may increase the risk of bladder cancer.

• Personal history of bladder cancer. People who have had bladder cancer have an increased chance of getting the disease again.

Chlorine is added to water to make it safe to drink. It kills deadly bacteria. However, chlorine by-products sometimes can form in chlorinated water. Researchers have been studying chlorine by-products for more than 25 years. So far, there is no proof that chlorinated water causes bladder cancer in people. Studies continue to look at this question.

Some studies have found that saccharin, an artificial sweetener, causes bladder cancer in animals. However, research does not show that saccharin causes cancer in people.

People who think they may be at risk for bladder cancer should discuss this concern with their doctor. The doctor may suggest ways to reduce the risk and can plan an appropriate schedule for checkups.

Glossary Terms

A poisonous chemical used to kill weeds and pests. Also used in cancer therapy.

Any substance that causes cancer.

A chemical used to disinfect water and as a bleach.

A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer. It is also used to treat some types of kidney disease in children. Cyclophosphamide attaches to DNA in cells and may kill cancer cells. It is a type of alkylating agent. Also called CTX and Cytoxan.

The functional and physical unit of heredity passed from parent to offspring. Genes are pieces of DNA, and most genes contain the information for making a specific protein.

An animal or plant that gets nutrients by living on or in an organism of another species. A complete parasite gets all of its nutrients from the host organism, but a semi-parasite gets only some of its nutrients from the host.

Something that increases the chance of developing a disease. Some examples of risk factors for cancer are age, a family history of certain cancers, use of tobacco products, being exposed to radiation or certain chemicals, infection with certain viruses or bacteria, and certain genetic changes.