title: Characteristics and significance of minimal and maximal extrathyroidal extension in papillary thyroid carcinoma.
abstract: OBJECTIVE
  Maximal extrathyroidal extension (ETE) is known to be an important prognostic factor in papillary thyroid carcinoma (PTC). However, the significance of minimal ETE is controversial. The aim of this study was to investigate the clinicopathologic characteristics and prognostic significance of minimal vs maximal ETE in PTC.
  
  
  METHODS
  A group of 967 patients who underwent thyroidectomy for PTC in a tertiary hospital between January 2000 and December 2011 were studied retrospectively. Patients were classified into three groups: absence of ETE, and minimal and maximal ETE. The minimal ETE group was further categorized into two subgroups according to invasion of strap muscles or no invasion (STI+ and STI-).
  
  
  RESULTS
  Gender did not differ between the three groups of patients. The mean age of the patients with maximal ETE was significantly higher than in those belonging to the other groups. Tumor size, bilaterality, lymph node metastasis and stage increased significantly according to the degree of ETE. Recurrence and survival rates did not differ between the absence and minimal ETE groups, or between the STI- and STI+ subgroups of minimal ETE. However, the maximal ETE group had significantly higher recurrence and lower survival rates than the other groups (P<0.001).
  
  
  CONCLUSIONS
  Maximal ETE is a significant factor for poor prognosis. However, minimal ETE is not associated with increased recurrence or decreased survival in patients with PTC.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul 133-792, Republic of Korea.
authors.forename: Bong Joon
authors.initials: BJ
authors.lastname: Jin
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul 133-792, Republic of Korea.
authors.forename: Moo Keon
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul 133-792, Republic of Korea.
authors.forename: Yong Bae
authors.initials: YB
authors.lastname: Ji
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul 133-792, Republic of Korea.
authors.forename: Chang Myeon
authors.initials: CM
authors.lastname: Song
authors.affiliation: Department of Internal Medicine, College of Medicine, Hanyang University, Seoul 133-792, Republic of Korea.
authors.forename: Jung Hwan
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Hanyang University, Seoul 133-792, Republic of Korea. Electronic address: kytae@hanyang.ac.kr.
authors.forename: Kyung
authors.initials: K
authors.lastname: Tae
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D055815:Young Adult
keywords: Capsular invasion; Extrathyroidal extension; Papillary thyroid carcinoma; Prognosis; Recurrence; Strap muscle invasion