High Incidence of Distant Metastasis Is Associated With Histopathological Subtype of Pediatric Papillary Thyroid Cancer - a Retrospective Analysis Based on SEER.

Dalin Zhang,Liang He,Jiapeng Huang,Hao Zhang,Ping Zhang,Jingzhe Xiang,Wei Sun,Zhihong Wang,Zhiqiang Gui,Chengzhou Lv,Liang Shao,Ting Zhang,Mengsu Cao,Wenwu Dong,Xue Zeng

doi:10.3389/fendo.2021.760901

Abstract

ObjectiveChildren with papillary thyroid cancer (PTC) have a higher invasive rate and distant metastasis rate, but the mortality rate is lower with unknown reasons. The majority of PTC cases comprise classical papillary thyroid carcinoma (CPTC) and follicular variant papillary thyroid carcinoma (FVPTC). This study aimed to determine the relationship between histopathological subtype and rate of distant metastasis and investigate factors influencing distant metastasis in pediatric PTC.MethodsA total of 102,981 PTC patients were recruited from SEER registry, 2004-2015. Proportion of distant metastasis between children (≤18 years) and adults with different histopathological subtypes was compared by propensity score matching. The cut-off age for distant metastasis in children was calculated by receiver operating characteristic (ROC) curve, and the risk factors for distant metastasis in pediatric patients were analyzed by logistic regression models.ResultsAmong the 1,484 children and 101,497 adults included in the study, the incidence of CPTC patients with distant metastasis in children was higher than that in adults (p<0.001). The ROC curve was calculated, which yielded a cut-off age for distant metastasis in CPTC children as 16 years old. In CPTC, the proportion of young children (2-16 years) with distant metastasis was higher than that of adolescents (17-18 years) and adults (>18 years) (both p<0.001). While there was no such trend in FVPTC. In young children (2-16 years), the incidence of CPTC with distant metastasis was higher than FVPTC (p=0.006). There was no difference between the proportion of CPTC and FVPTC with distant metastasis in adolescents (17-18 years) and adults. Logistic regression models revealed that extrathyroidal extension, lymph node metastasis and CPTC histopathological subtype were risk factors for distant metastasis in young children aged 2 -16 years.ConclusionsIn CPTC, the incidence of distant metastasis in young children (2-16 years) was significantly higher than that in adolescents (17-18 years) and adults (>18 years). In patients with distant metastasis aged 2-16 years, the proportion of CPTC was higer than that of FVPTC. Extrathyroidal extension, lymph node metastasis, and CPTC histopathological subtype were risk factors for distant metastasis in young children aged 2-16 years.

Highlights

Thyroid cancer is the most common endocrine cancer in the pediatric population [1]
In a cross-sectional study based on the Surveillance, Epidemiology, and End Results (SEER) database including individuals younger than 20 years who had a diagnosis of thyroid cancer, the incidence of pediatric thyroid cancer increased by 1.1% per year from 1973 to 2006, with a significant increase of 9.5% per year from 2006 to 2013 [2]
distant metastasis (DM) occurred in 999 patients (0.97%), ETE occurred in 18,204 patients (17.68%), lymph node metastases (LNM) occurred in 24,636 patients (23.92%), and 43,804 patients (42.54%) had multifocal tumors

Summary

Introduction

Thyroid cancer is the most common endocrine cancer in the pediatric population [1]. In a cross-sectional study based on the Surveillance, Epidemiology, and End Results (SEER) database including individuals younger than 20 years who had a diagnosis of thyroid cancer, the incidence of pediatric thyroid cancer increased by 1.1% per year from 1973 to 2006, with a significant increase of 9.5% per year from 2006 to 2013 [2]. Compared to adult thyroid carcinoma, the prognosis of pediatric papillary thyroid cancer is generally fair [3]. The reported mortality rate of pediatric papillary thyroid cancer (PTC) is very low with a higher rate of distant metastasis (DM) in most series despite more advanced disease at presentation and a higher risk of recurrence [4,5,6]. A study involving patients aged 12 to 83 years showed that approximately half of patients with welldifferentiated thyroid cancer with DM die of disease within 5 years of initial diagnosis despite thyroid surgery and radioactive iodine (RAI) [7]. Pediatric PTC patients aged less than 18 years might benefit from tailored disease management by cut-off age and expect better prognosis

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Results

Conclusion