EPIDEMIOLOGY

Bladder cancer is the ninth most common cancer in the world, with more than 400,000 new cases diagnosed in 2012. In the United States, approximately  17,000 deaths occur each year due to bladder cancer. Bladder cancer is often urothelial carcinoma.

Bladder cancer is typically diagnosed in older individuals, with a median age at diagnosis of 69 years in men and 71 in women. Although extremely rare, bladder cancer can be seen in children and young adults, where it usually presents with low-grade, non-invasive disease.
 

RISK FACTORS 

Chemical carcinogenesis — Chemical carcinogenesis is believed to be responsible for much of the burden of bladder cancer, including the increased risk associated with cigarette smoke as well as various industrial exposures. The relationship of bladder cancer to chemical carcinogens was initially suggested by the high incidence of bladder cancer in workers with particular chemical exposures.

Cigarette smoke — Cigarette smoking is the most important factor contributing to the overall incidence of urothelial cancer in western countries. The carcinogenic compounds present in cigarettes that are responsible for bladder cancer have not been definitively identified. There are over 60 known carcinogens and reactive oxygen species present, including 4-aminobiphenyl (4-ABP), polycyclic aromatic hydrocarbons, N-nitroso compounds, and unsaturated aldehydes.

The extent of smoking appears to be related to the aggressiveness of bladder cancer. In a study of 740 patients diagnosed over a 22 year period, heavy smokers (≥30 pack years) were more likely to have a high-grade tumor and to have muscle invasive disease at their original presentation compared with non-smokers.

Smoking cessation — Smoking cessation decreases but does not eliminate the increased risk of bladder cancer.

Secondhand smoke — Exposure to secondhand smoke in women appears to be a risk factor for the development of bladder cancer.

Occupational carcinogen exposure — Occupations that have been linked to an increased risk of bladder cancer include metal workers, painters, rubber industry workers, leather workers, textile and electrical workers, miners, cement workers, transport operators, excavating-machine operators, and jobs that involve manufacture of carpets, paints, plastics, and industrial chemicals.