What is bladder cancer?

Bladder cancer starts in the cells of the bladder. The bladder is in the lower part of the abdomen. It is a hollow, balloon-shaped organ with a flexible, muscular wall. The bladder is part of the urinary system. Urine is made by the kidneys. It is then passed to the bladder through 2 tubes called ureters. When the bladder is full, the muscles in the bladder wall tighten to force the urine out of the bladder. The urine empties out of the bladder and passes out of the body through a tube called the urethra.

Nearly all bladder cancers start in the lining of the bladder. Cancer that is only in the lining is called superficial bladder cancer. If the cancer spreads into the muscle wall of the bladder, it is called invasive bladder cancer.