Endocrine Abstracts

JOINT1639

Differentiated thyroid cancer (DTC) is rare in children requiring expert multidisciplinary management. The aim of this multicenter retrospective study by the national TUTHYREF network was to describe care pathway and outcome of these patients aged under 18. 93 patients, median age 15 years, managed for CPT between 2010 and 2022 were included. Surgery was performed by a pediatric surgeon in 14% of cases, in a university hospital in 53% of cases, with validation of surgical extension by a multidisciplinary team in 32% of cases. All patients underwent total thyroidectomy followed by radiotherapy (RAI). Central and lateral lymph node dissection was performed in 79 and 45% of cases respectively, with 19% R1 resection. Definitive hypoparathyroidism occurred in 5% of patients. Most patients had papillary DTC (84%), tumor size greater than 20 mm (45% pT2, 16% pT3), lymph node involvement (LNI) (21% N1a, 38% N1b), vascular invasion (42%), extra-thyroid invasion (37%). All patients had at least one iodine treatment (median activity 80 mCi), with a median Tg of 3.4 ng/mL and positive Tg Ac in 21% of cases. After a course of iodine, 69% of patients had an excellent response to RAI. After RAI, persistent and metastatic disease were observed in 22% and 12% of patients respectively. Of the 15 patients with morphological locoregional persistence or recurrence, 60% underwent re-operation. Among the 11 metastatic patients, metastases were synchronous in 73% of cases, with a median number of iodine treatments of 3 (1-6) and a Tg at diagnosis of 123 ng/mL. At the end of a median follow-up of 8 years in these patients, 64% were in remission and 36% in biological or morphological persistence, and none were refractory to iodine. Children under 15 had more aggressive disease (higher Tg at 16 ng/mL vs. 1.4 and 23% metastases vs. 2%), but the remission rate remained comparable to patients over 18. After a median follow-up of 4 years (1-13), 92% of patients were cured, 4% had an indeterminate response and 4% stable metastatic disease. Our study confirms that LNI and metastatic disease are more frequent in children, with a prognosis and sensitivity to RAI that remain excellent. The care pathway seems very heterogeneous, sometimes lacking the pediatric or social psychological and genetic intervention that is usually recommended and raises the question of pediatric surgical expertise, always complicated to assess to avoid excessive LND or incomplete surgery.