Bladder cancer occurs when the cells in the bladder (a hollow pelvic organ that stores urine. Unlike normal cells, which divide and grow in an organized fashion, the cancer cells continue to divide until they form a growth or tumor (a mass of excess tissue). In some cases, the cancer cells even become invasive, spreading from the bladder lining (where they originate) through the bladder wall and into neighboring lymph nodes and organs. Over time, bladder cancer can spread to distant sites such as the lungs, liver and bones.

The bladder is a muscular organ located in the pelvis. It stores urine, which is produced when the kidneys filter the blood. The bladder can become smaller or larger depending on how much urine it holds. The average adult bladder can hold approximately 16 ounces (473 milliliters) of urine. Urine from the kidneys passes into the bladder through two thin tubes called ureters, and is eliminated from the body through a third tube called the urethra. In women, the urethra is very short and ends right in front of the vagina. A man’s urethra is longer because it runs through both the prostate gland and the penis.

The bladder is composed of many layers of cells. Most bladder cancers begin in the urothelium. Also called the transitional epithelium, this layer of urothelial cells lines the inside of the urethra, bladder, ureters and kidneys. In addition to the urothelium, bladder cancer can also affect other cell layers such as muscle and connective tissue in and around the bladder. Bladder cancer usually begins in the lining layer and then can grow into the bladder wall. As the cancer reaches the deeper layers, it becomes more serious and difficult to treat.

When patients are initially diagnosed with bladder cancer, the disease is confined to the bladder in approximately 74 percent of the cases. In 19 percent of cases, the cancer has spread to tissues around the bladder, and in 3 percent of cases, it has reached distant sites (metastasis).

According to the American Cancer Society (ACS), more than 67,000 new cases of bladder cancer will be diagnosed in the United States during 2007. In addition, almost 14,000 individuals will die of the disease. Despite the increased incidence, the rate of bladder cancer deaths is decreasing. In fact, there are more than 500,000 bladder cancer survivors in the United States today.

Bladder cancer occurs nearly four times more often in men than in women. Additionally, white people are diagnosed with bladder cancer nearly twice as often as black people, and Hispanics have the lowest bladder cancer rate of the three groups. Bladder cancer tends to affect elderly people. In fact, half of all bladder cancer patients are over the age of 73.

When this disease is detected and treated early, there is a very good chance for survival. Individuals who are diagnosed with bladder cancer when it is localized have a 94 percent 5-year survival rate. After the disease has spread regionally, survival drops by about half. Left untreated, bladder cancer can lead to additional medical complications and a poorer prognosis for recovery.