Bladder cancer occurs when there are abnormal, cancerous cells growing uncontrollably in the lining of the bladder, which is the hollow organ in the lower abdomen that stores urine. These cancerous cells begin to affect the normal function of the bladder and can spread to surrounding organs. Bladder cancer is the fourth most common cancer in men, and it is three times more common in men than women.

There are two types of bladder cancer: Nonmuscle-invasive bladder cancer, also called superficial bladder cancer, occurs when cancerous cells are contained in the lining of the bladder and have not invaded the bladder wall. This is considered early stage and represents about 70 to 75 percent of all diagnoses. Muscle-invasive bladder cancer occurs when the cancer invades the bladder wall. This is considered advanced stage and represents the other 25 to 30 percent of diagnoses. In some cases, muscle-invasive bladder cancer can also spread (metastasize) to surrounding organs or other parts of the body.