A malignant tumor growth within the bladder. Bladder cancers usually arise from the transitional cells of the bladder (the cells lining the bladder).

These tumors may be classified based on their growth pattern as either papillary tumors (meaning they have a wart-like lesion attached to a stalk) or nonpapillary tumors. Nonpapillary tumors are much less common, but they are more invasive and have a poorer prognosis.

General information about Bladder Cancer

Bladder cancer is the fifth most common cancer in the United States. The American Cancer Society (ACS) estimates that in 1998, approximately 55,000 new cases of bladder cancer will be diagnosed, and it will cause at least 12,500 deaths. The disease is three times more common among men than women, and the iNational Cancer institutedence is also higher in Caucasians.

The urinary bladder is a hollow muscular organ that stores urine from the kidneys until it is excreted out of the body. Two tubes called the ureters bring the urine from the kidneys to the bladder. The urethra carries the urine from the bladder to the outside of the body.

Bladder cancer has a very high rate of recurrence. Even after superficial tumors are completely removed, there is a 75% chance that new tumors will develop in other areas of the bladder. Hence, patients need very frequent and thorough follow-up care.

Causes of Bladder Cancer

As with most other cancers, the exact cause is uncertain. However, several factors may contribute to the development of bladder cancer.

Cigarette smoking has been shown to increase the risk of developing bladder cancer by a factor of nearly five, compared to non-smokers. As many as 50% of all bladder cancer in men and 30% in women may be attributable to cigarette smoke. This risk, however, does show a gradual decline in individuals who quit smoking.

Studies show that one in four cases of bladder cancer can be attributed to occupational exposure to known carcinogens. Arylamines are a group of chemicals which are responsible for most occupational exposures. Dye workers, rubber workers, aluminum workers, leather workers, truck drivers, and pesticide applicators are at the highest risk; however, the presence of arylamines has been reduced or eliminated in many settings. The association between artificial sweeteners and bladder cancer has been studied and is weak or non-existent.

Women who received radiation therapy for the treatment of cervical cancer have an increased risk of developing transitional cell bladder cancer, as do some people who received the chemotherapy drug, cyclophosphamide (Cytoxan).

Chronic (long term) bladder infection or irritation may lead to the development of squamous cell bladder cancer, however, this cancer is very slow growing. Bladder infections do not predispose to transitional cell cancers.

In third world countries, infection with a parasite (schistosomiasis) has been linked to the development of bladder cancer.

Bladder cancers are classified or staged based on their aggressiveness and the degree that they are different from the surrounding bladder tissue (differentiation). There are several different ways to stage tumors; recently the TNM staging system has become more common. This staging system contains several substages, but it basically categorizes tumors using the following scale: