Ibrance is a very recent cancer medication. Has not been around for 6 years. Do not mistake cycles or round per years. In UK was approved in 2017 and US if I'm not mistaken 2015,but never six years ago. All the best. I would like to know if 75mg work as good but I guess that at the moment, being early years of palbociclib (Ibrance) there's not enough data to be 100% sure.
All the best