2.1
The most common form of bladder cancer is transitional cell carcinoma. Non-muscle-invasive transitional cell carcinoma is classified as stage Ta when it is confined to the uroepithelium and stage T1 when it has spread into the connective tissue layer between the urothelium and the muscle wall. Non-muscle-invasive transitional cell carcinomas usually appear as small growths from the bladder lining. They can be graded from G1 (low grade, least aggressive) to G3 (high grade, most aggressive). Carcinoma in situ consists of aggressive cancer cells that spread within the surface lining of the bladder and appear flat. It is more likely to recur after treatment.