Bladder cancer is classified based on the type of cells it contains. The main types of bladder cancer are:
- Transitional cell bladder cancer: About 90% of bladder cancers are urothelial carcinomas – cancers that begin in the urothelial cells, which line the inside of the bladder. Cancer that is confined to the lining of the bladder is called non-invasive bladder cancer. Urothelial cancers can develop anywhere from the renal pelvis, the ureters, the bladder, and the urethra.
- Squamous cell bladder cancer: This type of bladder cancer begins in squamous cells, which are thin, flat cells that may form in the bladder after long-term infection or irritation. These cancers occur less often than transitional cell cancers, but they may be more aggressive.
- Adenocarcinoma: Bladder cancer that develops in the inner lining of the bladder as a result of chronic irritation and inflammation. This type of bladder cancer tends to be aggressive.
- Other rare subtypes (e.g. small-cell carcinomas of the bladder)