This is an excellent question. I have not seen a lot of data out there about long-term survival, but know that we had one person on the forums that went through over 40 cycles of Vidaza before going to transplant, and I have heard stories from my doctor of people that have been on for 60 months or more. I know that this is not the norm, but there are certainly cases where people have had great success with extended Vidaza treatment. Recent research suggests that best response may not occur until about 11 or 12 months in many patients, and the duration of best response is variable.
I wish I could provide a more scientific answer, but looking through the articles, this does not seem to be a question that is really reviewed, or it is possible that there just isn't enough data available. Onee older study had transfusion independence periods that lasted 5 to 7 years, or more in a small percentage of cases.
http://jco.ascopubs.org/content/24/2...expansion.html
Hope this helps.