Your questions are very good, and I answer them below briefly in the interest of expediency, not to be rude.
1. Some knowledge is shared in journals; most knowledge isn't published until years after it's established. Much is never published, and is learned through word of math, and institutionally encoded. MD Anderson is world-renowned for being a center for excellence in cancer care.
2. Doctors don't read every article published in every journal related to their work. Even if they did, or read much of it, synthesizing into practice is a very different (and difficult) matter. Many of them don't read at all.
3. Why would MDs want to be send worldwide? And why would MD Anderson want to send them all over? Who pays for this? How can a doctor affect change in a large hospital system?