Clinical Implications of Age in Differentiated Thyroid Cancer: Comparison of Clinical Outcomes between Children and Young Adults

Background. Pediatric patients with differentiated thyroid cancer (DTC) present with unique characteristics compared to adult patients. This study aimed to evaluate clinical presentation and surgical outcomes according to age and to identify the clinical significance of age in DTC. Methods. In total, 98 pediatric patients, 1261 young adult patients, and 4017 adult patients with DTC who underwent thyroid surgery between January 1982 and December 2012 at Yonsei University Hospital (Seoul, Republic of Korea) were retrospectively reviewed. The mean follow-up duration was 120.4 ± 54.2 months. Results. Mean tumor size was significantly larger in the pediatric group than in the adult groups p<0.001. The recurrence rate was significantly higher in the pediatric group (14.3% versus 6.6% versus 3.0%, p=0.004 and p<0.001). In multivariate analysis, the risk of disease-free survival (DFS) was lower in the adult group (HR, 0.362; p<0.001). Reanalysis of patients with tumor size of 2-4 cm revealed that the adult group was not a significant risk factor for DFS in multivariate analysis (HR, 0.305; 95% CI, 0.158 to 0.588; p<0.001). Conclusions. Our findings suggest that pediatric patients present with more aggressive features and higher recurrence rates compared to adult patients and should be carefully treated from initial evaluation to surgery and postoperative care.