Would you treat an unresectable papillary thyroid carcinoma metastasis to the nasopharynx with skull base and perineurial invasion with radioactive iodine, radiation therapy, or chemo-radiation?

I would use external beam radiotherapy or even SRS if volume, size and location of the tumor permit. It is unclear if patient's thyroid cancer is RAI avid. Regardless, given skull base invasion, RAI alone may not suffice.