Dear OncoLink "Ask The Experts,"
Do you have any information on using BCG to reduce the size of bladder tumors in dogs?
Lili Duda, VMD, Section Editor of the OncoLink Veterinary Oncology Menu, responds:
BCG, or bacillus Calmette-Guerin is a bacterial vaccine that is a non-specific immunomodulator--in other words, it generally stimulates the body's immune system. In a few specific situations this results in a response against some types of cancer. Several decades ago BCG showed some positive results when instilled into the bladders of people with very superficial bladder cancers. Superficial bladder cancers are only a few cell layers thick and are confined to the inner lining of the bladder, and the BCG (or other drugs instilled directly into the bladder) could be absorbed into the superficial layers of the bladder and reach all the cancer cells. Many human bladder tumors are diagnosed at a very early stage, for a variety of reasons. Unfortunately, bladder tumors in cats and dogs are virtually never diagnosed at this early stage--they are already invasive tumors that are thousands and millions of cell layers thick and invade through the entire bladder wall. As a result, any drug instilled into the bladder only reaches a tiny percentage of the cancer cells and has no effectiveness. Systemic treatments are generally required and Feldene may help.