ESPE Abstracts

Objectives: American Thyroid Association (ATA) and European Thyroid Association (ETA) published guidelines about evaluation, treatment and follow-up. Despite these recommendations, published data on this subject is insufficient. This study aims to investigate the outcome of pediatric DTC and factors predicting the response to therapy in pediatric DTC.

Methods: Medical records of 46 children diagnosed with DTC, between 2000 and 2023 years, <18 years of age, were recorded. Patient’s demographics, medical history, surgical approach, pathology, radioactive iodine treatment (RAIT) and postoperative surveillance, including Tg, Tg antibodies (Tg Abs) and radiological imaging were evaluated. Median duration of follow up was 9.89(1-23.2) years. Regarding to 2015 ATA Guideline, patients with low and intermediate risk were included in group1 and with high risk in group2. Clinical response to treatment at 1 and 5 years were determined by unstimulated Tg levels, neck ultrasound and thyroid scintigraphy. Unstimulated Tg <1 ng/mL and AntiTg Ab negative and no lesion in imaging, termed as complete response. A rising Tg level and a significant rise in Tg antibodies suggests disease persistance.

Results: Papillary, follicular and medullary thyroid cancer were diagnosed in 84.8% (n = 39), 10.9% (n = 5) and 4.3% (n = 2) of the patients respectively. 16 children were determined to be in low, 11 in intermediate and 19 in high-risk diseases. Mean age of the patients were 11.72±3.80 years and 80.4% (n = 37) were female. All of the patients in high risk and intermediate risk received RAIT except 1 patient with medullary cancer. Among 16 patients with low risk, 7 did not receive RAIT (43,8%) and were in complete response at the end of 1 year. At the end of 1 year,24 of the patients in group1 and 3 of the patients in group2 had complete response. In the 5th year 8 patients with persistent disease were disease free. At the end of follow up, 35 (76,1%), 7 (15,2%) and (2,2%) patients were with no evidence, persistent and progressive diseases respectively. Only 3 patients didn’t complete 5 years follow-up period. At the end of the first and fifth years, complete remission rates in patients with low and intermediate risks were higher than in patients with high risk (P <0.001). ATA risk stratification, lymph node involvement, distant metastasis and capsular invasion were the most significant prognostic factors associated with response to therapy.

Conclusion: Despite aggressive nature of pediatric thyroid cancer at presentation, the prognosis is relatively fair. Low-risk DTC avoids exposure to radiation and doesn’t have a negative impact on remission rates.

Keywords: American Thyroid Association; European Thyroid Association; Pediatric Differentiated Thyroid Carcinoma; Radioiodine therapy