Risk of Structural Persistent Disease in Pediatric Patients with Low or Intermediate Risk Differentiated Thyroid Cancer

Purpose: In pediatric patients with differentiated thyroid cancer (DTC), the risk of recurrence is high and the indication for postoperative I administration is still debated. The aim of this study was to assess the outcome in low and intermediate risk pediatric DTC patients.

Methods: We retrospectively evaluated 45 pediatric patients with low or intermediate risk DTC, treated with surgery and I between 1992 and 2002 and with no detectable antithyroglobulin (Tg) antibodies. Follow-up was performed every 6-12 months with Tg blood level determination and imaging procedures.

Results: During follow-up (64 ± 53 months), 15 events occurred (33% cumulative event rate, with an annual event rate of 5% person years). Five of these patients were submitted to additional surgery and all these 15 patients underwent a second I treatment course. All patients were alive at the end of the follow-up. Structural persistent disease occurred more frequently in patients at intermediate risk (p < 0.01) and in those with Tg values after thyroid hormone withdrawal >10 ng/ml before I therapy (p < 0.01). At multivariate analysis, only a postoperative thyroid stimulating hormone-stimulated Tg level >10 ng/ml was an independent predictor of persistent disease.

Conclusions: In pediatric patients with DTC, postoperative high stimulated Tg values (>10 ng/ml) should be taken into account for deciding the extent of both initial treatment and follow-up.