A risk factor is anything that changes your chance of getting a disease such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer. Smoking is a risk factor for many cancers, including lung and bladder cancer. But risk factors don't tell us everything. Having a risk factor, or even several, does not mean that you will get the disease.

Many people with one or more risk factors never develop bladder cancer, while others with this disease have no known risk factors. It is important, however, to know about risk factors so that a person can take appropriate actions such as changing a health behavior or being monitored closely for a potential cancer. Because the bladder is the final exit from the body for many chemicals, these are the major risk factors for bladder cancer.

Smoking

The greatest risk factor for bladder cancer is smoking. Smokers are more than twice as likely to get bladder cancer as nonsmokers. Smoking causes about half of the deaths from bladder cancer among men (48%) and almost a third of bladder cancer deaths in women (28%). Some of the carcinogens (cancer-causing chemicals) in tobacco smoke are absorbed from the lungs and get into the blood. From the blood, they are filtered by the kidneys and concentrated in urine. These chemicals in urine damage the cells that line the inside of the bladder. This damage increases the chance of cancer developing.

Workplace exposures

Certain industrial chemicals have been linked with bladder cancer. Chemicals called aromatic amines, such as benzidine and beta-naphthylamine, which are sometimes used in the dye industry, can cause bladder cancer.

Other industries that use certain organic chemicals also may put workers at risk for bladder cancer if exposure is not limited by good workplace safety practices. The industries carrying highest risks include the makers of rubber, leather, textiles, and paint products as well as printing companies. Other workers with an increased risk of developing bladder cancer include painters, hairdressers, machinists, printers, and truck drivers (these because of exposure to diesel fumes).

Cigarette smoking and workplace exposures may act together to cause bladder cancer. Also, smokers who work with the cancer-causing chemicals noted above have an especially high risk of developing bladder cancer.

Race

Whites are about twice as likely to develop bladder cancer as African Americans and Hispanics. The reason for this difference is not well understood. Asians have the lowest incidence of bladder cancer.

Age

The risk of bladder cancer increases with age. Over 70% of people with bladder cancer are older than 65 years old.

Gender

Men get bladder cancer at a rate 4 times greater than women.

Chronic bladder inflammation

Urinary infections, kidney and bladder stones, and other causes of chronic bladder irritation have been linked with bladder cancer (especially squamous cell carcinoma of the bladder), but they do not necessarily cause bladder cancer. Schistosomiasis (also known as bilharziasis), an infection with a parasitic worm called Schistosoma hematobium that can get into the bladder, is also a risk factor for bladder cancer. In countries where this parasite is common, squamous cell cancers of the bladder are seen much more often. This parasite is an extremely rare cause of bladder cancer in the United States.

Personal history of bladder cancer

Urothelial carcinomas can form in many areas in the bladder as well as in the lining of the kidney, the ureters, and urethra. Having a cancer in any part of the urinary tract lining puts you at higher risk of forming another tumor. The tumor can form in the same area as before, or in another part of the urothelium (lining). This is true even when the first tumor is completely removed. For this reason, people who have had bladder cancer need close, routine medical follow-up.

Bladder birth defects

Before birth, there is a connection between the belly button and the bladder. This connection, called the urachus, normally disappears before birth. If part of this connection remains after birth, it could become cancerous. Cancers that start in the urachus are usually made up of malignant gland cells and are adenocarcinomas. Cancer starting in this way is rare, causing less than a half of 1% of bladder cancers. However, it does represent about one third of the adenocarcinomas of the bladder, which are also rare.

There is another rare birth defect called exstrophy, which greatly (about 400-fold) increases a person's risk of developing bladder cancer. In exstrophy, the skin, muscle, and connective tissue in front of the bladder fail to close completely so that there is a hole or defect in the wall of the abdomen. This leaves the inside of the bladder exposed to chronic infection, which may eventually lead to formation of an adenocarcinoma of the bladder.

Genetics

People who have family members with bladder cancer have an increased risk of getting it themselves. In some cases, these family members were all exposed to the same cancer- causing chemical. Another factor may be that their bodies are slow to break down toxins. This is determined by certain genes they inherit (like GST and NAT). People who inherit versions of these genes that lead to slow breaking down of chemicals are more likely to develop bladder cancer.

Bladder cancer does seem to run in some families. For a small number of people, this is because they inherited a gene syndrome, for example:

• A mutation of the retinoblastoma (Rb1) gene can cause cancer of the eye in infants, and also increases the risk of bladder cancer.

• Cowden disease, caused by mutations in a gene called PTEN, is linked to cancers of the breast and thyroid. People with this disease also have a higher risk of bladder cancer.

• Hereditary nonpolyposis colorectal cancer (HNPCC) syndrome (also known as Lynch syndrome) is mainly linked to colon and endometrial cancer. People with this syndrome also have an increased risk of bladder cancer.

Chemotherapy and radiation therapy

High doses of the chemotherapy drug cyclophosphamide (Cytoxan) or ifosfamide (Ifex) increase the risk of bladder cancer. A drug called mesna can be used with these drugs to protect the bladder from irritation and decrease the risk of bladder cancer.

People who are treated with radiation to the pelvis are more likely to develop bladder cancer.

Arsenic

Arsenic in drinking water has been associated with an increased risk of bladder cancer. The chance of being exposed to arsenic depends on where you live and whether you get your water from a well or from a system that meets the standards for arsenic content.

Low fluid consumption

Not drinking enough fluids increases the risk of bladder cancer. People who drink a lot of fluids each day have a lower rate of bladder cancer. This is thought to be because they empty their bladders often. By doing this, they keep chemicals from lingering in their bodies.

Last Medical Review: 01/27/2009
Last Revised: 5/13/2009