The bladder is a hollow organ that collects urine from the kidneys through the ureters for storage and eventual removal from the body through the urethra. Bladder cancer is the abnormal growth of bladder cells and is a common cancer; men have a higher risk of getting bladder cancer than women. The most common symptom of bladder cancer is bleeding in the urine (hematuria). The prognosis of bladder cancer ranges from good to poor and depends on the stage and grade of the cancer. People may reduce the risk of bladder cancer by not smoking and by avoiding environmental carcinogens. The exact cause of bladder cancer is unknown. It occurs when abnormal cells grow and multiply quickly and uncontrollably, and invade other tissues.