The exact cause of bladder cancer is not yet clear but certain factors that increase the risk of developing this condition have been identified.
Cancer begins with a change in the genetic “blueprint” or DNA of the cell, which is contained in the nucleus. This DNA provides the cell with the instructions necessary for its growth, maturity, function and eventually death. A change in the structure of DNA is called a mutation.
Normally, DNA damage is either repaired or the cells dies, but in the case of cancer, a cell containing abnormal DNA does not get repaired and still goes onto survive. The abnormal cell then proliferates, giving rise to further abnormal cells and eventually a tumor.
Several factors are known to increase the risk of these DNA mutations occurring. Some of these include:
Age – Bladder cancer usually occurs in people aged over 55 years and the average age-at-diagnosis is 73 years.
Gender – Men are about three to four times more likely to develop bladder cancer than women are. However, women are at a greater risk of developing an invasive type of cancer that has a poorer outlook.
Smoking – Smoking tobacco is the most important risk factor for bladder cancer. Studies have shown that smokers are at a significantly greater risk of bladder cancer than people who do not smoke or who only smoke for a short time.
Exposure to harmful chemicals – Exposure to certain chemicals is another important cause of bladder cancer. Exposure to chemicals in the workplace (such as aniline dyes, 2-aaphthylamine, 4-Aminobiphenyl, xenylamine and benzidine) has been linked to an increased risk for bladder cancer.
Arsenic – Exposure to arsenic has been linked to bladder cancer. In some parts of the world, high levels of arsenic are found in drinking water.
Previous history of bladder cancer – People who have been treated once for non-invasive bladder cancer are at risk of the cancer recurring. They are also at risk of the cancer returning as a more aggressive, invasive form.
Previous cancer therapy – People who have been treated with chemotherapy drugs such as cyclophosphamide are at an increased risk for bladder cancer. Radiotherapy also increases this risk, especially if the treatment was directed at the abdomen or pelvis.
Family history of bladder cancer – People with a first degree relative such as a parent or sibling who has had bladder cancer are at an increased risk of developing this cancer.
Reviewed by Sally Robertson, BSc