Hey. I had thyroid cancer five years ago. They won't know there and then. A biopsy takes a sample and they'll have to test it. I got an appointment a week later to get the result but I am in Ireland so the NHS might give the results differently. Unfortunately, the results can even then be inconclusive and they could have to repeat it 

I didn't have any symptoms - I think that is common with thyroid cancer. A doctor just noticed a lump on my neck and said it should be checked just to see what was causing it. 

Thyroid nodules are common and the majority are benign. Only about 5% are cancerous. I was just unlucky.

And even in the worst case scenario, well, my endocrinologist told me "ah, it's not the worst situation in the world." Not how it FEELS when you've just been diagnosed with cancer but it's rarely life-threatening and doesn't require ongoing treatment. I was sick from the anaesthetic for a couple of days after the operation but otherwise, I've been gone ever since.