Bladder cancer is a malignant overgrowth of cells in the bladder. The most common location of overgrowth is in the bladder cavity, which is the bladder’s mucosal epithelium.
In the human body, the surface of hollow organs is usually made up of epithelial cells. For example, the inside of your cheek, stomach, intestines, gallbladder, and bladder are all made up of a layer of epithelial cells.
Each organ has its own type of epithelial cells. The mucosal epithelial cells of the bladder are called urothelial cells, and the cancers that arise from them are called urothelial carcinomas, which account for 90%-95% of all bladder cancers and are the most common type of bladder cancer.
Other less common bladder cancers include squamous cell carcinoma and adenocarcinoma.