Background: Management of patients with thyroglobulin (Tg)-positive/scan-negative thyroid cancer remains challenging. American Thyroid Association (ATA) guidelines recommend potential use of empiric 131I therapy and various scanning modalities, but no standard for managing such cases exists. Methods: We surveyed ATA members to assess current practice in management of patients with Tg-positive/scan-negative disease. Members participated in a web-based survey of six case scenarios of Tg elevations but iodine scan negativity. Results: A total of 288 ATA members (80% male) participated. Patient age, sex, and basal and stimulated Tg varied between the cases. Respondents were asked their opinion regarding empiric 131I therapy use, including 131I dose, use and duration of low-iodine diet, thyroxine withdrawal or recombinant human thyrotropin (rhTSH), and utilization of additional imaging (neck ultrasound (US) or positron emission tomography/computed tomography (PET/CT)) and reconsideration of 131I therapy. Between 16% and 51% recommended initial use of empiric 131I for the various scenarios. The majority chose a 131I dose between 75 and 150 mCi, and 73% employed a low-iodine diet for two or more weeks. Preference between thyroxine withdrawal versus rhTSH was evenly split. More than 98% obtained a neck US if empiric 131I was not given; 52-89% would proceed to PET/CT if US was negative. Only 44% used rhTSH stimulation in PET scan preparation. 131I use was more common with stimulated Tg significantly >10ng/mL. 131I therapy was slightly more likely with PET-positive (56%) than PET-negative status (45%). Respondents were split regarding empiric 131I if basal and stimulated Tg increased ≥150% over two years. Providers in North America less commonly utilized 131I treatment than those from other areas. In the face of possible heterophilic antibody interference in the Tg assay, the majority did not recommend 131I therapy. Conclusions: Empiric 131I therapy is still utilized for patients with Tg-positive/scan-negative disease. Neck US is frequently used to further evaluate such cases as 18FDG-PET/CT, albeit the latter is used somewhat less often. Use of 131I therapy correlated with the degree of Tg elevation or development of Tg antibodies, and was recommended more commonly with PET-positive than PET-negative status in patients with lower Tg levels. 131I was less commonly used by providers within North America.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism