There are basically two types of treatments into the bladder BCG and mytomicin. BCG is supposedly the best. It is a derivative of the tuberculosis virus. It causes irritation in the bladder that helps kill cancer cells. It is usually once a week for about 6 weeks after which time the doctor does a cystoscopy and looks in the bladder and decides what to do based on what he sees. in my case I ended up with a cystectomy anyway as I had a bladder perforation that would not heal and because of the type pf cancer I had the Doctors felt it was safer to remove the bladder. I had a neobladder created that works real well. Needless to say I am very greatful to G_D and the Doctors. It has been 2 years now. I am 59.
BCG causes some irritation when you urinate right after you have received the treatment. the effect is temporary, the pain is not bad at all and more than pain it is uncomfortable. It is also uncomfortable to receive the treatment as they insert something like a foley tube through which they inject the medication. It is really not too bad. Tell your Grandpa that it is more being uncomfortable than painful and that in many cases although it is not really a cure it does work. You have to monitor yourself with the Urologist to make sure it is working and not progressing into the muscle layer of the bladder.
Hope this helps
Take care, good luck and keep the faith
Luis