Differentiated thyroid cancer: clinical characteristics, treatment, and outcome in patients under 21 years of age who present with distant metastases. A report from the Surgical Discipline Committee of the Children's Cancer Group.

BACKGROUND/
PURPOSE: Young patients with differentiated thyroid cancer typically present with regional lymph node involvement (60% to 80%), and 10% to 20% have distant metastases. This study characterizes the clinical presentation, treatment, and outcome in patients with differentiated thyroid cancer who were less than 21 years of age at diagnosis and who presented with distant parenchymal metastases.
METHODS: A retrospective, multi-institutional data base that included 327 patients in this age group with differentiated thyroid carcinoma was searched for patients who presented with distant metastases, and 83 cases (25%) were found. The median time to first disease progression was 2.4 years (range, 0.1 to 12.4 years) and the overall median follow-up was 10.9 years (range, 1.0 to 42.1 years).
RESULTS: The median age at diagnosis was 14.6 years (range, 6.6 to 20.8 years); 69% were girls and 92% were white. In 12%, there was a history of prior head and neck irradiation, and 10% of these patients had a family history of carcinoma. Preoperative needle biopsies were performed in 25%. Regional lymph nodes were positive in 90%, and extrathyroidal extension occurred in 48%. The site of distant metastases included the lungs in all patients. Total thyroidectomy, subtotal thyroidectomy, lobectomy, and nodule excision was done in 66%, 24%, 3%, and 8% of patients, respectively. There was no residual cervical disease after surgery in 75%, whereas 14% had microscopic and 11% had gross residual. Histopathologic subtypes included papillary-follicular (48%), papillary (42%), and follicular (10%). The median tumor size was 3.0 cm (range, 0.4 to 11.0 cm). In this group, 100% of patients received adjuvant iodine 131I therapy, and the overall survival rate at 10 years was 100%. The progression-free survival rate was 76% at 5 years and 66% at 10 years from diagnosis.
CONCLUSIONS: A significant number of young patients with thyroid cancer present with distant metastases and will require radioiodine therapy. This should be considered when planning the surgical approach because total or subtotal thyroidectomy facilitates 131I imaging and treatment. Although about one third of these patients will experience relapse or disease progression, the overall mortality rate is low.