I'm sorry you have anxiety as a result of the rise in tumor marker. I have a great deal of experience with this anxiety, and empathize. I have had PDTC with two rare mutations since late 2021, have endured two surgeries, two RAI treaments (the second of which proved I was RAI refractory) and 8 weeks of radiation last summer. I have TG tests every 3 months and what I've learned is that disease present does not necessarily present itself on a PET CT or U/S of the neck until your numbers reach beyond 100. So, for instance, after my first surgery and RAI treatment, my TG hovered between 0.2 and 0.9 for about a year before the number started to rise, sometimes exponentially between tests. My team did all the requisite imaging-- nothing popped up. I was told that for quite a long time, the disease will remain at microscopic stage: remember, a normal TG reading in a person with no cancer or thyroid disease can measure up to 40. That kind of number in thyroid cancer patient, who no longer has a thyroid, is of concern-- but in my case, the second mass was not found until my TG number shot up to 150. Good luck and know that there is a community here to help.