Prognostic Value of Tumor Multifocality in Pediatric Papillary Thyroid Carcinoma: A Real‐Life Multicentric Study

Abstract Objective To investigate the association of multifocality with clinical outcomes in pediatric papillary thyroid cancer. Study Design Multicenter retrospective study of prospectively collected data. Setting Tertiary referral center. Methods This study included patients 18 years or younger who underwent total thyroidectomy and radioiodine ablation for papillary thyroid carcinoma (PTC) between 2005 and 2020 at 3 tertiary adult and pediatric hospitals in China. For disease‐free survival (DFS), events were defined as persistent and/or recurrent diseases. The primary outcome was the association of tumor multifocality and DFS, assessed using Cox proportional hazards regression models. Results One hundred and seventy‐three patients (median age 16 years [range, 5‐18 years]) were recruited. Multifocal diseases were seen in 59 patients (34.1%). After a median follow‐up of 57 (range, 12‐193 months) months, 63 (36.4%) patients had persistent diseases. There was a significant association between tumor multifocality and decreased DFS on univariable analysis (hazard ratio [HR] = 1.90, p = .01), yet it was nonsignificant after multivariate adjustment (HR = 1.20, p = .55). In a subgroup analysis of 132 pediatric patients with clinically M0 PTC, neither unadjusted HR (2.21, p = .06) nor adjusted HR (1.70, p = .27) of multifocal PTC was significantly higher in comparison to unifocal PTC. Conclusion In this highly selective surgical pediatric patient cohort with PTC, tumor multifocality was not an independent risk factor for decreased DFS.