title: Postoperative ultrasonography surveillance in patients with follicular thyroid carcinoma: a multicenter study.
abstract: OBJECTIVE
  This study aimed to evaluate the locoregional recurrence rate of follicular thyroid carcinoma (FTC) and to assess the appropriate frequency of postoperative ultrasonography (US) surveillance for detecting tumor recurrence.
  
  
  METHODS
  The review boards of the seven participating institutions approved this study. From 2000 to 2011, 186 patients underwent at postoperative US at least once; US was performed by experienced radiologists at each institution. Based on the US and histopathological results, locoregional tumor recurrence was assessed.
  
  
  RESULTS
  The T stages of the 186 patients were T1a (8.1%), T1b (21.5%), T2 (39.8%), T3 (30.6%), T4a (0%), and T4b (0%). The N stages were unknown (24.2%), N0 (71.5%), N1a (3.2%), and N1b (1.1%), and the M stages unknown (29.6%), M0 (66.1%), and M1 (4.3%). Tumors recurred in only 6 (3.2%) patients during the follow-up period over 5 years. Among them, no patients showed the initial suspicion of recurrences on routine follow-up US. The session number and interval of postoperative US differed significantly between patients with recurrence and those without recurrence. The mean interval of postoperative follow-up US at the first detection time of tumor recurrence was 37.5 ± 18.5 months (range 9-62 months). Significantly more FTCs were at an advanced N and M stage in the recurrence group than in the non-recurrence group (p < 0.05).
  
  
  CONCLUSIONS
  Routine postoperative US surveillance may be unnecessary for detecting tumor recurrence after thyroid surgery in FTC patients.
authors.affiliation: Department of Radiology, Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon, 51476, South Korea.
authors.forename: Hye Jin
authors.identifier: http://orcid.org/0000-0001-7349-2841
authors.initials: HJ
authors.lastname: Baek
authors.affiliation: Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, 75, Bokji-ro, Busanjin-gu, Busan, 47392, South Korea. dwultra@nate.com.
authors.forename: Dong Wook
authors.identifier: http://orcid.org/0000-0002-9826-1326
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea.
authors.forename: Song
authors.identifier: http://orcid.org/0000-0002-2367-3588
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine, Seoul, 08308, South Korea.
authors.forename: Inseon
authors.identifier: http://orcid.org/0000-0001-6866-7926
authors.initials: I
authors.lastname: Ryoo
authors.affiliation: Department of Radiology, Research Institute and Hospital, National Cancer Center, Gyeonggi, 10408, South Korea.
authors.forename: Chang Yoon
authors.identifier: http://orcid.org/0000-0001-8645-3569
authors.initials: CY
authors.lastname: Lee
authors.affiliation: Department of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, South Korea.
authors.forename: Yoon Jung
authors.identifier: http://orcid.org/0000-0001-7223-5421
authors.initials: YJ
authors.lastname: Choi
authors.affiliation: Department of Radiology, Thyroid Center, Daerim St. Mary's Hospital, Seoul, 07442, South Korea.
authors.forename: Jin Yong
authors.identifier: http://orcid.org/0000-0002-8163-4624
authors.initials: JY
authors.lastname: Sung
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology; D009367:Neoplasm Staging; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D013965:Thyroidectomy / Q000379:methods*; D016896:Treatment Outcome; D014463:Ultrasonography / Q000379:methods*
keywords: Follicular thyroid carcinoma; Recurrence; Thyroid; Thyroidectomy; Ultrasonography