I use the date I was diagnosed as my anniversary. But I wont forget the day my porta cath was fitted as it was my birthday and my first chemo was my wedding anniversary. It was very romantic day, not, as I looked anything but attractive wearing the cold cap, lol. At least this year I can celebrate in a bit more style for both.
I remember the day of my operation, especially as it is the day before my husband's birthday which, in turn, is the day before Valentine's Day. (Not much hope of me forgetting it is there?)
I use the date of diagnosis which unfortunately for me was also my bithday !! Bitter sweet for me but one thing I will say is before bc I used to say I dont really celebrate birthdays now im getting older WELL I DO NOW, I am 3 years from dx next week and its my birthday on saturday, I gather the family and we all celebrate together , how bc changes your perspective on things eh
But you are right some choose the day of finishing treatment as there date, others when the cancer was removed, its a personal choice I suppose