Bladder cancer is the fourth most common cancer in men and the eighth most common cancer in women. About 80,000 people in the United States are estimated to be diagnosed annually. Bladder cancer starts when the cells that make up the urinary bladder begin to grow out of control. As more cancer cells develop, they can form tumors and, over time, spread to other parts of the body.
The bladder is a hollow organ in the lower pelvis. Its main function is to store urine. Urine is liquid waste made by the kidneys and then carried to the bladder through tubes called ureters. When you urinate, the muscles in the bladder walls contract, and the urine is forced out of the bladder through a tube called the urethra.