LONG-TERM FOLLOW-UP STUDY OF JUVENILE DIFFERENTIATED THYROID CARCINOMA TREATED BY RADIOACTIVE IODINE

Abstract

The overall prognosis in pediatric differentiated thyroid carcinoma (DTC) is excellent. Recurrent disease is frequent, however, and requires additional treatment. In this study we retrospectively analyzed the outcome of juvenile DTC treated by radioactive iodine (I-131) during the long-term follow-up study of 29 years. Methods: 54 DTC patients (34 females, 20 males; ≤20 years old, mean age, 16,5 years) were treated with 131I (RAI) with a median follow-up of 13 years. Patients (pts) underwent different initial treatment: 49 pts, TTx+RAI; 2 pts, TTx; and 3 pts, STTx. The probability of recurrence and prognostic factors were tested by Kaplan-Meier’s method. Results: Initially, 37/54 pts achieved complete remission (CR), 16/54 pts partial remission (PR), 1/54 had progressive disease (PG). During the follow-up 11 pts (20,4%) who achieved CR developed recurrent disease (RD); median appearance time, 4 years (range, 1–25 years). Probability of recurrence was 15,8% at 5 years; 20,3% at 10 years, 25,6% at 15, 20 and 26 years after initial treatment. Strong predictive factors of recurrence were age (p=0,0001), initial treatment (p=0,0001), and tumor multifocality (p=0,004), while gender, nodal metastases at presentation, distal metastases at presentation, histological type of the tumor, tumor or T stage and clinical stage showed no influence on relapse (p=0,176; p=0,757; p=0,799; and p=0,822, respectively). Patients with RD, PR and PG were retreated, with surgery or surgery plus RAI, receiving cumulative activity up to 40 GBq. The overall outcome in our patients was excellent: 88,9% CR, 5,55% SD, 1,85% PG, 1,85% DRD, and 1,85% OCD. Conclusion: Younger age at diagnosis, less radical primary surgery without subsequent RAI, and tumor multifocality are strong prognostic factors for recurrence. In order to reduce relapse rate and to improve surveillance for recurrent disease, TTx followed by RAI appears to be the most beneficial initial treatment for patients with juvenile DTC. The use of RAI seems to be safe without adverse effects on subsequent fertility and pregnancy or secondary malignancy.