title: The effect of external beam radiotherapy volume on locoregional control in patients with locoregionally advanced or recurrent nonanaplastic thyroid cancer.
abstract: OBJECTIVE
  We evaluated outcomes of patients treated with external beam radiotherapy (EBRT) for locoregionally advanced or recurrent nonanaplastic thyroid cancer and analyzed the effect of EBRT volume on locoregional control.
  
  
  METHODS
  This study included 23 patients with locoregionally advanced or recurrent nonanaplastic thyroid cancer who were treated with EBRT. Two different EBRT target volumes were executed as follows: 1) limited field (LF, n = 11) included the primary (involved lobe) or recurrent tumor bed and the positive nodal area; 2) elective field (EF, n = 12) included the primary (involved lobe) or recurrent tumor bed and the regional nodal areas in the cervical neck and upper mediastinum. Clinical parameters, such as gender, age, histologic type, recurrence, stage, thyroglobulin level, postoperative residuum, radioiodine treatment, and EBRT volume were analyzed to identify prognostic factors associated with locoregional control.
  
  
  RESULTS
  There were no significant differences in the clinical parameter distributions between the LF and EF groups. In the LF group, six (55%) patients developed locoregional recurrence and three (27%) developed distant metastasis. In the EF group, one (8%) patient developed locoregional recurrence and one (8%) developed a distant metastasis. There was a significant difference in locoregional control rate at 5 years in the LF and EF groups (40% vs. 89%, p = 0.041). There were no significant differences in incidences of acute and late toxicities between two groups (p >0.05).
  
  
  CONCLUSIONS
  EBRT with EF provided significantly better locoregional control than that of LF; however, further larger scaled studies are warranted.
authors.affiliation: Center for Thyroid Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea. k2onco@ncc.re.kr
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.forename: Ki-Wook
authors.initials: KW
authors.lastname: Chung
authors.forename: You Jin
authors.initials: YJ
authors.lastname: Lee
authors.forename: Chan Sung
authors.initials: CS
authors.lastname: Park
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Lee
authors.forename: Tae Sung
authors.initials: TS
authors.lastname: Kim
authors.forename: Seok Ki
authors.initials: SK
authors.lastname: Kim
authors.forename: Yoo Seok
authors.initials: YS
authors.lastname: Jung
authors.forename: Jun Sun
authors.initials: JS
authors.lastname: Ryu
authors.forename: Sang Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Kwan Ho
authors.initials: KH
authors.lastname: Cho
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Shin
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011379:Prognosis; D011878:Radiotherapy / Q000379:methods*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology / Q000532:radiotherapy*