Endocrine Abstracts

Introduction: The majority of patients with radioiodine-refractory thyroid carcinoma (RAIR-TC) have an indolent disease and require active surveillance (AS) only, while those with progression of the disease (PD) may benefit from local treatment (LT) or systemic therapy with tyrosine-kinase inhibitors (TKI). In the literature, no data about the real impact of LTs in avoiding/delaying systemic treatment in RAIR-TC patients are present.

Objective: This study describes the impact of LTs in patients with RAIR-TC in progression not treated with TKI.

Patients and Methods: We retrospectively evaluated 279 patients RAIR-TC, referred to our institution from January 2016 to December 2021. Clinical examination, serum markers measurements and neck ultrasound were performed every 6-12 months. Disease staging was assessed by Total Body Computed Tomography and/or other imaging exams (Magnetic Resonance Imaging, Positron Emission Tomography/Computed Tomography and Bone Scintigraphy). PD was defined according to RECIST 1.1. Definition criteria of RAIR-TC and the indication to start a LT or systemic therapy with TKI were determined according to 2016 ATA guidelines.

Results: After the diagnosis of radioiodine-refractoriness (RR), 176/279 (63.1%) patients presented a PD. Of this group, 33/176 (18.7%) patients were assigned to AS, 44/176 (25.0 %) to LTs and 99/176 (56.3%) to TKI. Regarding the 44/176 (25.0%) patients that receiving LTs, the mean time from the initial diagnosis to the end of the follow-up was 12.8 years (interval 1.5-33.7 years). A total of 74 LTs were performed in the 44 patients. In particular, the following LTs were performed: 31/74 (42.0%) surgical treatment of local recurrence or lymphadenectomy, 19/74 (25.7%) external beam radiation therapy on the neck, 9/74 (12.2%) external beam radiation therapy on the bone metastases, 4/74 (5.4%) radiofrequency thermal ablation of local disease/lymph node metastases, 2/74 (2.7%) surgical excision of bone metastases, 2/74 (2.7%) surgical excision of lung metastases, 2/74 (2.7%) endoscopic laser unblocking and tracheal recanalization, 2/74 (2.7%) trans-arterial chemoembolization or radioembolization of liver metastases, 1/74 (1.3%) surgical excision of pancreatic metastases, 1/74 (1.3%) external beam radiation therapy on pulmonary metastases and 1/74 (1.3%) stereotaxic radiosurgery on brain metastases. The mean time from the first LTs to the end of the follow-up was 2.6 years (interval 0.6-20.4 years). During the follow-up after LTs, no patient started TKI and no patient deceased.

Conclusions: This study showed that 25.0% of RAIR-TC patients had a PD of either single lesions or single organs that can be treated with LTs. These LTs allowed to avoid or delay the systemic therapy with TKI that, as known, has a rather relevant impact on the quality of life of these patients.