They don't know what causes thyroid cancer. Genes, environmental factors, exposure to radiation? When you go to the dentist and they cover you with a big heavy protective blanket during x-rays which includes a collar, they are protecting your thyroid from radiation. (I always think they can skip that for me.) It is thought that exposure to radiation through xrays or radiation as a child can cause thyroid cancer. But apparently if you are near nuclear reactor fallout you have a greater chance.
But the cancer cause mystery prevails. They have thoughts but no real idea. Well, keep thinking because I'm still waiting. While you are at it, you can find a cure too. Thank you.