Paul, the terms "T1 and T2" refer to the
stage of the tumor...that is, how far it has progressed. For BCG, what is most important is the "grade."
www.cancer.net/cancer-types/bladder-cancer/stages-and-grades?sectionTitle=Staging
BCG is most effective for HIGH GRADE tumors, that is those that are rapidly dividing. T1 or T2 tumors can be either low grade or high grade. CIS is ALWAYS high grade and requires immediate treatment because high grade tumors have the potential to get out of hand rather quickly. BCG is also effective against high grade "T" tumors, but not so much when they are low grade. Bladder cancer has a nasty little habit of recurring; when low grade bladder cancer comes back over and over, BCG is often tried.
CIS is somewhat like a rash on the surface of the bladder. It is diffuse and, therefore, cannot easily be removed as many of the papillary form of tumors can be. BCG is an attenuated (modified) tuberculosis bacterium that was developed many many years ago as a vaccination for children against TB. It is instilled into the bladder as a wash and its purpose is to stimulate, or activate, the immune system to reject the foreign cancer cells in the bladder lining.
BCG does have some side effects, the most common being fatigue, urinary urgency, and bleeding. These are usually short-lived and show that the immune system is being stimulated. In many cases, such as mine, this keeps the cancer from returning.
The "best practice" protocol for CIS is for an initial 6 week series of BCG installations. Then, a few months later, a "maintenance" regimen is started. The exact timing of this can vary, but mine was to have BCG every three weeks every three months until two years had passed. It has been shown that the maintenance protocol increases the effectiveness of the BCG significantly.
You absolutely want to follow your urologist's recommendations; it does appear that they are "right on" for treatment of CIS. You will also want to keep your appointments for re-checks scrupulously. Like all bladder cancer, CIS can recur...the BCG is meant to help avoid that..but if not treated it can quickly spread.
I hope that I have answered some of your questions, including those you posted below. CIS is not good news (no bladder cancer is) but in most cases it is highly treatable, particularly when diagnosed and treated promptly!
Sara Anne