Poster Session : PS 1297 ; Endocrinology : Cases of Differentiated Thyroid Carcinoma Which Ended Up Poor Prognosis after Radioidoine Ablation Treatment = Poster Session : PS 1297 ; Endocrinology : Cases of Differentiated Thyroid Carcinoma Which Ended Up Poor Prognosis after Radioidoine Ablation Treatment

다국어 초록 (Multilingual Abstract)

Background: L-thyroxine (LT4) withdrawal is a commonly used method prior to radioactive iodine (RAI) ablation treatment in differentiated thyroid cancer (DTC) patients. However, a prolonged period of hypothyroidism may reduce quality of life in DTC patients. Furthermore, LT4 withdrawal may have trophic effect on residual cancer by increased TSH and deteriorate cardiac function. We reported two cases of high-risk DTC patients with malignant pleural effusion who underwent rapidly worsening of the disease after LT4 withdrawal and RAI therapy. Patient findings: The first case involved a 65-year-old women who had papillary thyroid cancer with multiple distant metastases and malignant pleural effusion. During LT4 withdrawal for the RAI therapy, rapid worsening malignant pleural effusion required repetitive therapeutic thoracentesis. The second case involved a 49-yearold woman who had papillary thyroid cancer and had undergone three additional operations for neck lymph node cancer recurrences and four RAI treatments. During planning the 5th RAI therapy with LT4 withdrawal, malignant pleural effusion was developed, and it was progressively aggravated after RAI treatment. Both of two cases were high-risk patients accompanied with extra-thyroidal invasion and LN metastasis at the time of the diagnosis. Both experienced increased pleural effusion during the LT4 withdrawal period and a rise in the thyroglobulin level after RAI therapy. Malignant pleural effusion was not controlled with therapeutic thoracentesis and pleurodesis. Eventually, both of them came to death due to rapid disease progression after RAI treatment. Conclusion: LT4 withdrawal for RAI treatment may be harmful in high-risk DTC patients, especially with distant metastases and malignant pleural effusion.