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. BCG solution may help the body’s immune system kill cancer cells. Also called bacillus Calmette-Guérin solution.