Thyroid cancers are a completely different family of cancer than what we normally talk about here. They are endocrine system cancers, which if caught early are surgically resolved and then a life time of synthetic hormones takes care of the lack of a thyroid. Essentially those of us that are acutely hypothyroid from radiation are on the same regime as someone that has had the surgery. It would seem odd for you to get it, but after Hiroshima there were a ton of these in that exposed survivor population, so it is clear that radiation can cause them. Good luck with this, enlargement may not = serious.