I have Osteopenia as well as breast cancer diagnosis and Hiatus Hernia, and get fantastic quotes from Insurance With. My anual world wide this year was under £100.
congratulations on finishing your active treatment.
Like you in the past I always had a cheap annual europe-wide insurance with no conditions declared, and now of course I got a BC diagnosis 18 months ago, and also arthritis (but not osteoporosis thank goodness!)
I got a worldwide annual travel insurance with "Insure for Travel" for about £200 with the bc and the arthritis declared as I plan to go to S America early next year. I always buy annual as i like to have lots of cheap breaks, but I did look into a single trip policy for the Americas, and on top of the European policy it wasn't any cheaper that a worldwide annual (including America) which would then cover for anything. "All Clear" also would have covered me but was a bit more expensive.
You might want to go on Moneysaving Expert website where you can get a variety of quotes after you have put in your medical history. There is a particular part of the site just for people with pre-existing medical conditions. Hope you have a great holiday. xx