Clinical features, treatment, and long-term outcome of papillary thyroid cancer in children and adolescents without radiation exposure.

BACKGROUND: Cancer of the thyroid gland is rare in children and adolescents. A history of neck irradiation is a well-established risk factor for tumor development, and most previous reports focused on cases that were induced by radiation exposure. We present here a retrospective review of the clinical features, treatment, and long-term outcome of children and adolescents with papillary thyroid cancer (PTC) without a history of radiation exposure who were treated at our institution over a period of ~50 years.
METHODS: We retrospectively investigated 142 PTC patients without an irradiation history who were younger than 20 years of age when treated from 1961 to 2005 (17 males and 125 females; mean age = 16.3 ± 2.7 years; follow-up = 21.8 ± 12.0 years). The clinicopathological results were evaluated using the medical records. Disease-free survival (DFS) and cause-specific survival (CSS) were assessed with the Kaplan-Meier method and compared with the log-rank test. Parametric analyses were performed using Student's t test and nonparametric analyses were performed using the Mann-Whitney U test.
RESULTS: At diagnosis, three patients had distant lung metastasis and 33 had gross neck lymph node (LN) metastasis. All patients were treated with surgery (hemi/partial thyroidectomy in 45 patients, subtotal thyroidectomy in 85, total thyroidectomy in 12, no LN dissection in 50, central compartment dissection in 20, and modified radical neck dissection in 72), and postoperative external beam radiation therapy was administered to 59. Postoperative ablative therapy using I(131) was not performed in this series. Recurrence was found for regional LN (n = 25), lung (n = 9), remnant thyroid (n = 5), and others (n = 4). DFS and CSS at 40 years were 74.1 and 97.5%, respectively. DFS was significantly worse in patients aged <16 years with a family history of thyroid cancer, preoperative neck gross LN metastasis, maximum tumor diameter, and extrathyroidal invasion. Preoperative gross neck LN metastasis and distant metastasis at diagnosis were significant factors for CSS. No other factors contributed to DFS and CSS. When the clinical features of children and adolescents were compared, the incidence of preoperative gross neck LN metastasis and distant metastasis at diagnosis and tumors with a maximum diameter >10 mm were significantly higher in the children group than in the adolescent group. DFS was significantly shorter in the children group than in the adolescent group, but no significant difference was found in CSS between these two groups.
CONCLUSIONS: The prognosis of PTC in children and adolescents is excellent, regardless of the extent of thyroidectomy and LN dissection. We recommend that only children or adolescents with preoperative gross neck LN metastasis and distant metastasis at diagnosis should be subjected to postoperative ablative therapy.