Graves’ orbitopathy development in thyroid cancer patients: A 16-year nationwide cohort study in South Korea

Abstract

Abstract Background/Objectives: Thyroid cancer patients, without history of hyperthyroid condition, suffer from Graves’ orbitopathy (GO). We investigated its incidence, possible risk factors and prognosis. Subjects/Methods: This study is a retrospective cohort study that analyzes medical records of 1,137,861 South Korean patients from 2002 to 2019. Those whom without hyperthyroidism or GO prior to thyroid cancer diagnosis were included. We investigated 8,499 individuals and compared the type of surgery, dose of radioactive iodine (RAI) and daily average thyroid hormone between GO group and non-GO group. In addition, each GO patient’s medical records were analyzed, and the course of disease and the type of treatment was described. Results Among 8,499 cancer patients, 7,836 cases received a thyroidectomy, and 12 were diagnosed with GO after surgery. None of the remaining 663 cases received a GO diagnosis. In addition, the GO group indicated a significantly higher total RAI dose average than the non-GO group (p = 0.036). Within the GO group, the approximate time from thyroid cancer diagnosis to GO occurrence was 460.5 (331.0-984.8) days. Five patients underwent RAI therapy before GO diagnosis. Of these, four expressed GO within a year post-RAI therapy, and the total iodine dose before GO was 168.5 (139.8-203.8) mCi. The average daily thyroid hormone dose before GO was 85 (70–120) µg. One case required intravenous and oral steroids Conclusions Although GO rarely develops in thyroid cancer patients without coexisting hyperthyroidism, the total RAI dose may increase its risk. Further study regarding its pathogenesis would help clarify GO’s association with thyroid cancer.