The urine is produced in the kidneys, then flows through tubes called the ureters into the bladder. From there it is discharged through the urethra during urination. The bladder muscle aids urination by contracting to help force out urine.
Bladder cancer occurs when cancer cells form in the tissues of the bladder. More than 90 percent of bladder cancer originates in the bladder lining (transitional cell carcinoma), and the majority of diagnosed tumors are confined to the lining. Other types of bladder cancer are squamous cell carcinoma and adenocarcinoma. Bladder cancer is the fourth most common type of cancer in men and the eighth most common type of cancer in women. Bladder cancer typically occurs in older people. Nearly 90 percent of people with bladder cancer are over the age of 55.