Bladder Cancer

What Is It?

Bladder cancer is an uncontrolled growth of abnormal cells in the bladder, the balloon like organ that stores urine.

Bladder cancer begins in the lining of the bladder. In 70 percent to 80 percent of people with bladder cancer, the cancer is discovered when it is still a limited, superficial problem. These superficial bladder cancers usually appear as an isolated patch of abnormal cells on the bladder lining or as an odd fingerlike projection along the bladder's inner wall. Less often, the tumor is diagnosed when it already has become invasive, which means the tumor has invaded deeply into the muscle of the bladder wall, spread (metastasized) to nearby lymph nodes or spread to distant organs.

There are three types of bladder cancer, which have different types of cells. About 90 percent of cancers in the bladder are transitional-cell carcinomas. The rest are either squamous-cell carcinomas (6 percent to 8 percent) or adenocarcinomas (2 percent).

The causes of bladder cancer are only partly understood. It is thought that the majority of transitional-cell carcinomas are caused by carcinogens (cancer-causing substances), such as tobacco smoke and chemicals in the environment. Smokers get bladder cancer two to four times more often than people who don’t smoke, although only about half of all bladder-cancer patients have ever been smokers. Bladder cancer also is associated with exposure to certain industrial chemicals, but exposure to such chemicals has been reduced dramatically by modern workplace safety laws. These industrial carcinogens include aniline dyes, polycyclic aromatic hydrocarbons (such as 2-naphthylamine, 4-aminobiphenyl or benzidine), polychlorinated biphenyls or chemicals used in aluminum manufacturing. These chemicals are used in the aluminum, rubber, chemical and leather industries, as well as by dry cleaners, chimney sweeps, hairdressers, painters, printers, textile workers, machinists and truck drivers. In developing countries, a parasitic infection called schistosomiasis increases the risk of developing bladder cancer.