Today my significant other took my Mom for her yearly Oncology appointment. The doctor said everything looked great and told my S/O there is no reason for her to keep coming back year after year.... and at 96 if she didn't get a blood disorder by now, chances are she won't.
Mom also has yearly mammograms... it's very difficult for her as she is frail, and it takes two techs to help her with the mammogram. I can understand Mom's concern as she had a sister who died from breast cancer, but that was 50 years ago and her other 4 sisters never got it, neither did her mother.
Mom insist on going for these yearly appointments.... maybe it's a reinforcement that everything is ok. I know if my doctor said no more mammograms I would be doing cartwheels :)
Since you can't fool her with a forgotten appointment, tell her what the doctor said "Mom, the doctor says you don't have to come in every year anymore. It is very unlikely you will have any problem." If she is very respectful of her doctor, this may work.
At that age, you need to catch problems as soon as possible lest they become more serious.
2. Perhaps she enjoys the attention she gets at doctors' offices. Some medical staff really fuss over their older patients. It's like a social even for the patients.
3. It gets her out of the house.
4. I can understand the cancer concern. I'm the only one in my paternal family who hasn't had it, and the possibility is always in the back of my mind.