I wouldn't worry about the cancer risk, it seems to be very rare. My mother had her gallbladder removed 44 years ago and is doing fine at 75 years old. If we worried about every study published about the "possible increased risks", we wouldn't take any medication or have any surgeries. That's not to say we shouldn't investigate and weigh the possible risks and problems that could arise from surgeries done to us, or medications we take, but we do need to have a balanced view. I would ask your doctor about the possible risks and let him weigh in on it with you. How many times have we seen studies contradicted later on?
I don't think the metamucil is a bad idea (if your doctor recommends it), since it is also known to lower cholesterol. It would be a win win for you if it worked