Bladder cancer is a disease in which malignant (cancer) cells form in the tissues of the bladder. The bladder is a hollow organ in the lower part of the abdomen. It is shaped like a small balloon and has a muscular wall that allows it to get larger or smaller to store urine made by the kidneys.
There are three types of bladder cancer that begin in cells in the lining of the bladder. These cancers are named for the type of cells that become malignant (cancerous): transitional cell carcinoma, squamous cell carcinoma and adenocarcinoma.
Cancer that is in the lining of the bladder is called superficial bladder cancer. Cancer that has spread through the lining of the bladder and invades the muscle wall of the bladder or has spread to nearby organs and lymph nodes is called invasive bladder cancer.