Cancer, including bladder cancer, develops because of changes in the DNA of a normal cell. DNA can be damaged by chemical exposures such as cigarette smoke, industrial chemicals, chemotherapy, and so forth. Environmental exposures such as these are called risk factors. Risk factors do not exactly cause bladder cancer. Not everyone who smokes will get bladder cancer. However, as a group, the risk is elevated relative to people who do not smoke.
Exposures such as these increase the likelihood of DNA becom-ing damaged. When the specific DNA that controls a cell’s growth is damaged, the cell then has the potential to become cancerous. The hallmark of cancer is overgrowth of cells, causing compression of surrounding tissues or destruction of the tissues.