First, I would review the pre-operation image to understand how extensive is the thymoma involved and then talk with the surgeon to find out where the high-risk area is. If the margin is negative and there is no trans-capsular invasion, I would not recommend post-OP RT. If there is a positive margin...

To me, aside from the pathological findings discussed by Dr. @Joe Y. Chang, the most important input is the surgeon’s concern about margins. There is no substitute for that experience and I almost always will irradiate if the surgeon is concerned. It is important also to bring the surgeon to t...