Oral Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

A Retrospective review of Radioactive Iodine Avidity in a Cohort of Patients with Oncoytic Thyroid Carcinoma; A Single Centre Review (128682)

Stephen Ludgate 1 2 , James McNeil 1 , Sarah C Brennan 1 , Ayanthi A Wijewardene 1 , Lyndal Tacon 1 , Venessa Tsang 1 3 , Bruce Robinson 1 3 , Roderick Clifton-Bligh 1 3 , Matti L Gild 1 3
  1. The Department of Diabetes, Metabolism and Endocrinology, Royal North Shore Hospital, St Leonards, NSW, Australia
  2. The School of Medicine, Trinity College Dublin, The University of Dublin, Dublin, Ireland
  3. School of Medicine, University of Sydney, Sydney, NSW, Australia

Oncocytic thyroid carcinoma (OTC), previously termed Hürthle cell carcinoma, represents 5% of all thyroid cancers. This follicular cell-derived neoplasm was recategorised as a distinct thyroid cancer subtype due to its unique molecular and pathologic characteristics. Clinical outcomes for OTC patients are worse than other forms of differentiated thyroid cancer (DTC). Widely invasive OTC subtype has been shown to have extensive vascular invasion and OTC was found to be less radioactive iodine (RAI) avid than other forms of DTC.1 RAI remains controversial in OTC and its utility is largely dependent on minimally or widely invasive phenotype.2  

We conducted a retrospective study, reviewing our electronic records to assess the response to RAI in patients with an OTC diagnosis, treated at our quaternary referral centre.

Data analysis revealed 49 patients with a diagnosis of OTC between 2012-2020, who underwent treatment with RAI. Mean tumour size was 38.1 mm (8–110mm) with 81.6% (40/49) showing vascular invasion. Extra thyroidal extension was seen on histology in 7 cases(14.3%). 26 cases(53.0%) received 4GBq of RAI activity, with the remainder receiving either 1,2,6 or 8 GBq of RAI activity based on risk stratification. Initial RAI ablation in 45 cases showed only residual iodine uptake in the thyroid bed, the thyroglossal duct tract or was reported as physiologic uptake. Four cases (8.2%) showed focal uptake away from these sites. 3/45(6.7%) cases, had proven metastatic disease on imaging or histology, which was not RAI avid. Six cases received repeat RAI treatment due to a rising thyroglobulin or disease progression. None (0/6) of these cases showed any focal iodine uptake away from the thyroid bed, despite this progression.

Our data on patients with OTC shows high rates of vascular invasion, and a RAI-refractory profile. As has previously been suggested, OTC warrants tailored patient care that differs from that of other DTCs.3

  1. 1. McFadden DG, Sadow PM. Genetics, diagnosis, and management of Hürthle cell thyroid neoplasms. Frontiers in endocrinology. 2021;12:696386.
  2. 2. Yang Q, Zhao Z, Zhong G, Jin A, Yu K. Effect of adjuvant radioactive iodine therapy on survival in rare oxyphilic subtype of thyroid cancer (Hürthle cell carcinoma). PeerJ. 2019;7:e7458.
  3. 3. Bischoff LA, Ganly I, Fugazzola L, et al. Molecular alterations and comprehensive clinical management of oncocytic thyroid carcinoma: a review and multidisciplinary 2023 update. JAMA Otolaryngology–Head & Neck Surgery. 2024;150(3):265-272.