A type of biologic therapy used to treat early stage bladder cancer. The solution is made from a weakened form of a bacterium called Mycobacterium bovis (bacillus Calmette-Guérin) that does not cause disease. It is given through a catheter that is placed into the bladder where the solution is held for about two hours. Bacillus Calmette-Guérin solution may help the body’s immune system kill cancer cells. Also called BCG solution.