Hi Sol, I found myself asking the very same question during my initial 6 wk treatment for T1G3 BC, and found that skipping a treatment was no big deal to my oncologist. If memory serves me well, I believe Dr. Lamm addressed this question on his website and that as far as I can recall, it didn't seem to be a problem. During my maintenance round of treatments, also scheduled for 6 weeks, not only did I have 3 treatment postponements, but the last 3 treatments ended up being 1/2 doses as well because I had some significant reactions to the BCG.
Sol, I have had two cysto's now (Dec 18/07 & Apr. 1/08)and am very happy to report that both times I've been BC free. My personal experience suggests that taking oncovite + green tea + pomegranate juice, and lots of H20 sure didn't hurt. I don't know if my experience will work for you since we are all different. I wish you well with the treatments and hope your oncologist explains the various aspects of your treatment regime to you.
Take care,
Gordo