TG and cancer: Many centers continue to simply repeat RT as long as there is visible 131I-avid lesions on Rx-WBS and/or elevated thyroglobulin (Tg) (6), yielding a potential overuse of 131I in patients with radioiodine-refractory disease (7) and increased risk of side effects, such as salivary gland dysfunction (8), pulmonary fibrosis (9), bone marrow suppression (10), and secondary cancers (11).