Differentiated thyroid carcinoma in childhood. Clinical experience up to five years follow up period after radioiodine treatment

Objectives Epithelial solid tumors are very rare in childhood and represent about 9% of all childhood cancers. However differantieted thyroid carcinomas (DTC) are the most common endocrine neoplasia (0,5-3%) of all childhood malignancies. Pediatric DTCs have some clinicopathological differences from the adult type cancers. This retrospective study investigates the clinical behaviour, pathological characteristics of childhood thyroid cancers and analyses the treatment options and outcomes.

Methods A total of 26 patients with differentiated thyroid carcinoma under age of 18 have undergone raidoiodine ablation following total thyroidectomy (twenty female and six male; mean age at diagnosis 14,3 ± 2,9 years). 22 patients had papillary thyroid cancer, 2 patients had follicular, 1 patient had papillary and follicular mixed, 1 patient had nonspecified well differentiated thyroid carcinoma. The mean diamater of all tumours was 2.6cm. The frequency of multifocality, capsule invasion and and lymph node metastasis were calculated as 11.5%, 42.3% and 53.8%, respectively. An absence of I-131 uptake in the neck and thyroglobulin levels of less than 1ng/ml when T4 suppression is withdrawn on the sixth month of radioiodine treatment were the criteria of ablation. The mean follow up time was 20.4 months.

Results As a result, 19 patients were totally ablated with a single dose of I-131 (2-4 GBq). 5 patients took a second dose of radioiodine for the residual tissue or lymph node in the neck and 1 patient received radioiodine again for lung metastasis. 1 patient left was 6 years old and has been recently given ablation. He had diffuse lung metastases which was detected on the sixth day postablation whole body scintigraphy and he is now under follow up.

Conclusions Different from adults, childhood thyroid cancers represent with lymph node and distant metastasis at diagnosis and tend to behave more aggressively. So a successful surgery and an effective radioiodine ablation have a crucial role for good outcomes