Pediatric thyroid cancer: Postoperative classifications and response to initial therapy as prognostic factors

Abstract

Context: Prognostic factors for pediatric differentiated thyroid cancer (DTC) are not well established. Objective: The objective of the study was to retrospectively compare the postoperative risk-stratification systems: American Thyroid Association (ATA) risk categories, Schneider Children's Medical Center of Israel (SCMCI) score, and the response to initial therapy as predictors for disease outcome. Patients and Methods: Fifty-four DTC patients, median age at diagnosis 13.9 years (range 1.9-17 y), followed up for a median of 8.8 years (range 2.6-20.5 y) were stratified into prepubertal (n = 9), pubertal (n = 25), and postpubertal (n = 20) groups. All patients underwent total/near-total thyroidectomy; 48 received radioiodine therapy. The extent of DTC was evaluated by applying the ATA risk categories and the novel SCMCI score. Postoperative risk stratifications (low/intermediate/high) were determined using histopathological, laboratory, and imaging findings. Response to initial therapy (complete/acceptable/incomplete) was based on stimulated thyroglobulin and imaging results during the first 2 years of follow-up. Results: The risk for recurrent/persistent disease, as assessed by the postoperative ATA risk-stratification system and the SCMCI score and by the response to initial therapy, was higher in the prepubertal group (P < .001, P = .002, and P = .02, respectively). Outcome prediction by the risk-stratification systems was applicable: ATA risk categories, P = .014, R2 = 0.247, predictive ability 80.4%; SCMCI score, P < .001, R2 = 0.435, predictive ability 86.3%; and response to initial therapy stratification, P