What Causes Bladder Cancer?

Reviewed by: HU Medical Review Board | Last review date: September 2017.

The causes of most bladder cancers are still not very well understood, but researchers are working to understand more about what causes cancer cells to develop and grow in the bladder. Key areas of research about the causes of bladder cancer include:

Genetic mutations and bladder cancer

Much research about the causes of cancer—including bladder cancer—is focused on the role of genetic mutations inside of cells, and how they can cause cancer cells to develop.1-3 All cells in the body contain genes made up of DNA, which controls how those cells work. Different genes control the different cell functions. For example, oncogenes are genes that control how cells grow, multiply, and stay alive. Tumor suppressor genes work by causing cells to die at the right time, and by repairing problems in the DNA. Changes to the DNA in cells are called gene mutations. According to the American Cancer Society, cancer can be caused by gene mutations inside of cells that “turn on” oncogenes or “turn off” tumor suppressor genes. Researchers have identified certain mutations, or combinations of mutations, in oncogenes and tumor suppressor genes that may be linked to different types of bladder cancers.

Genetic mutations passed down in families

Some genetic mutations are inherited, meaning they are passed down through families from parents to children on the DNA in their cells. There are rare inherited genetic mutations that can increase a person’s risk of bladder cancer, such as Cowden disease and Lynch syndrome. There are likely to be other genetic mutations linked to bladder cancer in the future as well because people are twice as likely to be diagnosed with bladder cancer if they have a close family member who has it.

Exposure to harmful chemicals

Evidence shows that if people are exposed to certain harmful substances over time—either in the home or in the workplace—then they have a higher risk of developing bladder cancer than people who are not exposed to those substances.2 This includes people who work in jobs where they are exposed to paints, metal, dyes, or petroleum products that contain harmful chemicals. Also at higher risk are people who have been drinking water for a long time from a well (or other source) that contains arsenic or chlorine.

Toxins in urine can damage the bladder lining

Researchers think the reason is that many types of harmful substances (also called toxins) are filtered out of the blood and removed from the body through urine. When people are exposed to large amounts of toxins on a regular basis at home or work, then those toxins can frequently be present in the urine. Toxins that are removed from the body in urine can damage the lining of the bladder over time, which increases the risk of bladder cancer.

Bladder cancer and inflammation

There is evidence to suggest that over time, chronic irritation and inflammation in the lower urinary tract is linked to an increased risk of bladder cancer, particularly a rarer type called squamous cell carcinoma.1,4 Sources of irritation and inflammation include chronic urinary tract infections, bladder stones, and kidney stones. Inflammation can also be caused by having a urinary catheter for a long time, or by a type of parasitic bladder infection (schistosomiasis) that is very rare in the United States. Bladder inflammation has not been proven to directly cause the cancer, although the role of inflammation in the growth and development of cancer cells is a major area of ongoing research.

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