So sorry to welcome you to our club! But you will find many people here who understand.
There were two pieces of bad news in that path report High grade means that it has the potential to spread. And it has already invaded the muscle. I would expect that your grandfather's urologist will recommend that the bladder be removed. If the cancer has not spread beyond the bladder, this CAN be curative.
Best wishes to you and your family.
Diagnosis 2-08 Small papillary TCC; CIS
BCG; BCG maintenance
Vice-President, American Bladder Cancer Society