hey there, Nelie! I will definitely ask my doctors their reasons. According to what they told me so far, the reason is that "they have had recurrence in such cases and do not want to risk". Another reason, they say, is the type of cancer (but I read here it is well/moderately differentiated so that sounds strange) and my age.
The protocols say I should not do it, but sometimes you don't know whether to agree with protocols or with humans... I think the docs are simply concerned about not making me take the risk of recurrence, and I certainly can understand that. On the other hand, I ask myself, what kind of risk is that, and does it really disappear with radiation?