How do you sequence I-131 and external beam radiation therapy after thyroidectomy for locally advanced thyroid cancer?

I've not had an occasion wherein I sequence a radiopharmaceutical and XRT for thyroid cancer, as a planned event.

Again, different indications for different therapeutics here. The radioisotope is designed to address I-avid, minimal volume disease while XRT is designed to treat macroscopic, generally...

In the setting where there is a potential indication for post-thyroidectomy EBRT, the risk of locoregional recurrence is presumably quite high. Therefore, usually will advocate to proceed with EBRT first, followed by RAI.