John Han-Chih Chang, MD and Kenneth Blank, MD
Ultima Vez Modificado: 1 de noviembre del 2001
Dear OncoLink "Ask the Experts,"
I am presently being treated with a drug named BCG for bladder cancer. The drug is placed into the bladder once a week for six weeks. The instructions make the material seem contaminating. Why does this material need to be treated so carefully?
John Han-Chih Chang, MD and Kenneth Blank, MD, OncoLink Editorial Assistants, respond:
Thank you for your interest and question.
BCG stands for Bacillus Calmette and Guerin. The therapy you have described is called intravesical (infusing into the urinary bladder) therapy. The "drug" is actually an attenuated strain of Mycobacterium bovis. These bacteria are relatives of the infectious agent known to cause tuberculosis. The fact that M. bovis is attenuated means that it is live bacteria, but not be able cause the infectious complications associated with tuberculosis. It is essentially a bacteria used to cause an immune/inflammatory reaction. In fact, BCG is used in many countries, other than the US, as a vaccine for tuberculosis.
BCG is usually utilized for early stage or superficial bladder cancers via the intravesical route. It is used after a transuretheral removal of the bladder tumors as an adjunct to the primary treatment, since recurrence rates can be from 30% to as high as 85% with transuretheral resection alone. Outside of BCG, other intravesical chemotherapy agents used in superficial bladder cancer are Thiotepa, Doxorubicin, and Mitomycin C.
Out of all the intravesical therapeutic agents, BCG appears to be the most promising in controlling this disease. The mechanism of action is not clearly understood. Intravesical BCG appears to promote a localized inflammatory reaction with histiocytic and leukocytic infiltration of the urinary bladder. This may promote an immune mediated cancer cell "killing." This remains purely speculative.
The side effects of treatment have been found to be local irritative symptoms, fever, pneumonitis, hepatitis, arthritis, arthralagias and skin rash. Thus, most of these complications of treatment are infectious/inflammatory due to the nature of the agent, but the lasting effects remain only temporarily. This may be why the instructions disclosed this to be a biohazard.
We hope this helps in the understanding of your treatment.