Bladder cancer occurs when abnormal cells in the bladder grow in an uncontrolled way. In some cases, the cancer can spread to other parts of the body.
The bladder is located in the lower abdomen (belly). It is a hollow organ with a muscular wall that allows it to get bigger or smaller as needed. The bladder stores urine until it is released from the body. When you urinate, the bladder muscle walls contract and the urine is forced out of the bladder through a tube called the urethra.
When cancer cells only occur in the lining of the bladder, this is called superficial bladder cancer.
If cancer cells spread into the muscle wall of the bladder or to other organs and lymph nodes, this is called invasive bladder cancer.