Prevalence and Risk Factors for Multifocality in Pediatric Thyroid Cancer

Importance: Current guidelines recommend total thyroidectomy for the majority of pediatric thyroid cancer owing to an increased prevalence of multifocality. However, there is a paucity of information on the exact prevalence and risk factors for multifocal disease - knowledge that is critical to improving pediatric thyroid cancer management and outcomes. Objective: To determine the prevalence and risk factors for multifocal disease in pediatric patients with papillary thyroid carcinoma (PTC). Design, Setting, and Participants: This multicenter retrospective cohort study included patients 18 years or younger who underwent thyroidectomy for PTC from 2010 to 2020 at 3 tertiary pediatric hospitals and 2 tertiary adult and pediatric hospitals in the US. Main Outcomes and Measures: Demographic and clinical variables, including age, family history of thyroid cancer, autoimmune thyroiditis, prior radiation exposure, cancer predisposition syndrome, tumor size, tumor and nodal stage, PTC pathologic variant, and preoperative imaging, were assessed for association with presence of any multifocal, unilateral multifocal, and bilateral multifocal disease using multiple logistic regression analyses. Least absolute shrinkage and selection operator analysis was performed to develop a model of variables that may predict multifocal disease. Results: Of 212 patients, the mean age was 14.1 years, with 23 patients 10 years or younger; 173 (82%) patients were female. Any multifocal disease was present in 98 (46%) patients, with bilateral multifocal disease in 73 (34%). Bilateral multifocal disease was more accurately predicted on preoperative imaging than unilateral multifocal disease (48 of 73 [66%] patients vs 9 of 25 [36%] patients). Being 10 years or younger, T3 tumor stage, and N1b nodal stage were identified as predictors for multifocal and bilateral multifocal disease. Conclusions and Relevance: This large, multicenter cohort study demonstrated a high prevalence of multifocal disease in pediatric patients with PTC. Additionally, several potential predictors of multifocal disease, including age and advanced T and N stages, were identified. These risk factors and the high prevalence of multifocal disease should be considered when weighing the risks and benefits of surgical management options in pediatric patients with PTC..