title: Pediatric patients with multifocal papillary thyroid cancer have higher recurrence rates than adult patients: a retrospective analysis of a large pediatric thyroid cancer cohort over 33 years.
abstract: BACKGROUND
  Large-sample studies with long-term follow-up data are limited for pediatric patients with thyroid cancer.
  
  
  OBJECTIVE
  Secular changes in clinicopathological characteristics and outcomes in pediatric patients with thyroid cancer were investigated and compared with those of adults.
  
  
  METHODS
  A retrospective review of 150 pediatric patients with thyroid cancer managed between 1980 and 2013 was conducted. The long-term outcomes of 124 patients followed up for 12 months or longer were evaluated. Predictors of recurrence-free survival (RFS) in pediatric patients with papillary thyroid cancer (ped-PTC group) were compared with those of 3071 adult patients.
  
  
  RESULTS
  The proportion of small tumors (<1 cm) increased from 9.0% before 2010 to 36.8% after 2010 (P < .001); however, neither pathological presentations such as multifocality, extrathyroidal extension (ETE), lymph node (LN) metastasis, or lung metastasis nor the RFS rate changed over time. The 5- and 10-year recurrence rates were 14.5% and 34.4% in pediatric patients, respectively. In respective analyses of the ped-PTC group and patients of all ages with papillary thyroid cancer (all ages group), the rates of ETE, LN metastasis, and lung metastasis were higher with younger age (all P for trend <.05). RFS was lower in the pediatric than the adult patients aged 20-54 years (P < .005) and was comparable with that of older patients (≥ 55 y). Only tumor multifocality and size predicted recurrence in the ped-PTC group (P < .05), whereas LN metastasis and ETE also predicted recurrence in the all-ages group (P < .01). Among patients in the all-ages group with multifocal tumors, pediatric patients had the lowest RFS (P < .05).
  
  
  CONCLUSIONS
  The pathological characteristics and recurrence rates of pediatric thyroid cancer have not changed over 33 years. Although younger patients present with more advanced disease, multifocality rather than age at diagnosis predicted recurrence. Recurrence was higher in pediatric than adult patients with multifocal papillary thyroid cancer.
authors: Department of Pediatrics (Y.A.L., H.W.J., H.Y.K., S.W.Y., C.H.S.), Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, 110-769, Korea; and Departments of Internal Medicine (H.C., D.J.P., Y.J.P.), Nuclear Medicine (J.J.-K.C.), Surgery (H.-Y.K.), and Otorhinolaryngology and Cancer Research Institute (J.H.H.), Seoul National University College of Medicine, Seoul 110-744, Korea.
authors: Young Ah
authors: YA
authors: Lee
authors: Hae Woon
authors: HW
authors: Jung
authors: Hwa Young
authors: HY
authors: Kim
authors: Hoonsung
authors: H
authors: Choi
authors: Hyun-Young
authors: HY
authors: Kim
authors: J Hun
authors: JH
authors: Hah
authors: Do Joon
authors: DJ
authors: Park
authors: June-Key
authors: JK
authors: Chung
authors: Sei Won
authors: SW
authors: Yang
authors: Choong Ho
authors: CH
authors: Shin
authors: Young Joo
authors: YJ
authors: Park
mesh_terms: D000293:Adolescent; D000328:Adult; D002277:Carcinoma / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D002291:Carcinoma, Papillary; D002648:Child; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology* / Q000473:pathology; D009378:Neoplasms, Multiple Primary / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D047368:Tumor Burden; D055815:Young Adult