Though the exact cause of bladder cancer remains unknown, certain risk factors have been identified which increase an individual’s likelihood of developing the disease. Risk factors associated with bladder cancer include:

• Age. The risk of developing bladder cancer increases with age. According to the American Cancer Society (ACS), about 70 percent of bladder cancer cases occur in patients age 65 or older.
  
  
• Gender. Men have a four times greater chance than women to develop bladder cancer.
  
  
• Smoking. Individuals who smoke develop bladder cancer twice as often as nonsmokers. According to the ACS, smoking is associated with 48 percent of bladder cancer deaths among men and 28 percent of bladder cancer deaths among women. The lungs absorb certain chemicals from tobacco. These chemicals are then passed into the bloodstream, filtered by the kidneys and collected in the urine. When these chemicals accumulate in the urine, they can damage the cells that line the bladder and thereby increase the risk of bladder cancer. In addition to tobacco, marijuana smoking has also been associated with a higher risk of bladder cancer.
  
  
• Work exposure. Certain types of jobs may increase an individual’s risk of developing bladder cancer because the employee is exposed to certain chemicals during the course of duty or in the workplace.  For instance, hairdressers, painters, printers, aniline dye workers, machinists and truck drivers all have a greater risk because their work involves environmental factors that may cause cancer. Individuals who work with tobacco products or are exposed to large amounts of secondhand smoke are also at risk for bladder cancer.
  
  
• Race. Whites have double the risk of developing bladder cancer compared to Hispanics and African Americans. The lowest rate of bladder cancer is found among Asians.
  
  
• Chronic bladder infection. Conditions such as urinary infections, bladder stones and kidney stones have been linked to bladder cancer, although they do not cause the disease.
  
  
• History of bladder cancer. Individuals who have had bladder cancer in the past are more likely to develop another tumor. People with a family history of bladder cancer also have a greater risk of developing the disease.
  
  
• Levels of angiogenin. Some research studies have shown that individuals with an elevated level of the antibody angiogenin may have an increased risk of bladder cancer. Additional research is necessary in this area.
  
  
• Bladder birth defects. Sometimes the connection between the bladder and navel in the fetus does not disappear before birth as it should and can become cancerous. Cancer associated with birth defects of the bladder is very rare.
  
  
• Genetic mutations. Risk for bladder cancer may be increased in people with a genetic mutation associated with retinoblastoma, an eye cancer most commonly seen in infants and young children.
  
  
• Previous treatment. Certain drugs or radiation used to treat other forms of cancer can increase bladder cancer risk in some individuals.
  
  
• Arsenic. An increased risk of bladder cancer has been linked to arsenic in drinking water.
  
  
• Parasitic infections. Being infected with certain parasites can increase bladder cancer risk. These parasites are not typically found in the United States.
  
  
• Hormones. Studies have indicated that hormonal factors may affect a woman’s chance of developing the disease. Women who enter menopause at an earlier age may have a higher risk of bladder cancer. Researchers speculate that lower estrogen levels may increase bladder dysfunction and be associated with frequent urinary tract infections, which are risk factors for the disease.

Certain other theories about bladder cancer risks have not been proven. For example, several artificial sweeteners have been associated with bladder cancer in laboratory animals when given in high doses, but the link in human cancer has not been established. Another piece of conventional wisdom has associated chlorinated water or chlorine by-products with bladder cancer. Researchers continue to study this issue, but no firm link has been established.