DefinitionBladder cancer is a cancerous tumor in the bladder. The bladder is the organ in the center of the lower abdomen that holds urine.Alternative NamesTransitional cell carcinoma of the bladder; Urothelial cancerCauses, incidence, and risk factorsIn the United States, bladder cancers usually start from the cells lining the bladder (transitional cells).These tumors are classified based on the way they grow:Papillary tumors have a wart-like appearance and are attached to a stalk.Nonpapillary (sessile) tumors are much less common. However, they are more invasive and have a worse outcome.As with most other cancers, the exact cause of bladder cancer is uncertain. However, several factors may contribute to its development:Cigarette smoking. Smoking increases the risk of developing bladder c