title: Time trend in tumour size and characteristics of anaplastic thyroid carcinoma.
abstract: OBJECTIVE
  Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies. Nevertheless, there have been reports that some patients experience long-term survival and those in whom ATCs of small size are often detected. We evaluated the time trend of characteristics of ATC such as size and association with coexistent differentiated thyroid carcinoma (DTC). We also found the characteristics of patients showing long-term survival.
  
  
  METHODS
  This is a retrospective observational cohort study from the two major tertiary referral hospitals in Seoul, Korea. Ninety-five patients who had been diagnosed with ATC from 1995 to 2010 were included. We classified them into three groups according to the time of initial diagnosis: group 1 (1995-1999), group 2 (2000-2004) and group 3 (2005-2010).
  
  
  RESULTS
  The mean tumour size decreased significantly according to groups; 6·2, 5·5 and 4·0 cm in group 1, 2 and 3, respectively (P = 0·02). The frequency of cases with coexistent DTC increased; 10·3%, 35·1% and 48·3% in group 1, 2 and 3, respectively (P = 0·02). Fifteen of 95 patients survived more than 24 months, and among them, 13 are still alive who underwent curative surgery. Among 15 long-term survivors, nine patients with ATC arising from DTC had ATC tumour portion less than 1 cm. Another five patients with ATC without coexistent DTC had relatively small-sized tumours (1·0-4·0 cm).
  
  
  CONCLUSIONS
  The tumour size of ATC decreased, and cases with coexistent DTC increased over the last two decades. We found that patients with ATC showing long-term survival are those who had atypical presentations such as anaplastic transformation in early stage of DTC or small size of tumours without coexistent DTC.
authors.affiliation: Department of Internal Medicine, Asan Medical Centre, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Ji Min
authors.initials: JM
authors.lastname: Han
authors.forename: Won
authors.initials: W
authors.lastname: Bae Kim
authors.forename: Tae Yong
authors.initials: TY
authors.lastname: Kim
authors.forename: Jin-Sook
authors.initials: JS
authors.lastname: Ryu
authors.forename: Gyungyub
authors.initials: G
authors.lastname: Gong
authors.forename: Suck Joon
authors.initials: SJ
authors.lastname: Hong
authors.forename: Jung-Han
authors.initials: JH
authors.lastname: Kim
authors.forename: Young Lyun
authors.initials: YL
authors.lastname: Oh
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Jang
authors.forename: Sun Wook
authors.initials: SW
authors.lastname: Kim
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Chung
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000473:pathology* / Q000601:surgery / Q000628:therapy; D002454:Cell Differentiation; D015331:Cohort Studies; D003131:Combined Modality Therapy; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016019:Survival Analysis; D065646:Thyroid Carcinoma, Anaplastic; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery / Q000628:therapy; D013965:Thyroidectomy; D013997:Time Factors; D055815:Young Adult