I don't know if "Happy Anniversary" is the appropriate thing to say...how
about,
"Thinking of you warmly on this remembrance of your illness."
Doesn't exactly sound like Hallmark, does it? :-)
I'm so sorry for all you've been through, but so glad you are on the tmic
list, not only for your benefit, but also for all the great help and
encouragement you give to others.
Barbara H.