title: Limited thymectomy for stage I or II thymomas.
abstract: BACKGROUND
  Once an anterior mediastinal tumor has been diagnosed as a thymoma, complete excision including the thymic gland and perithymic fat is currently the procedure of choice. However, little is known about the clinical outcome of grossly encapsulated thymomas excised only with the surrounding tissue while leaving a part of the thymic gland.
  
  
  METHODS
  A retrospective historical comparative study was conducted on 79 patients who had received surgery for stage I (n=25) or stage II (n=54) thymomas. Total thymectomy was performed in 61 patients (Total Thymectomy Group), whereas resection of tumors with only the surrounding tissue was carried out in 18 (Limited Thymectomy Group). The follow-up interval was longer in the Limited Thymectomy Group because these patients were treated longer ago (104.2+/-58.1 months vs 67.3+/-54.8 months, p<0.05).
  
  
  RESULTS
  One case in the Limited Thymectomy Group showed postoperative myasthenia gravis (5.6%). Two patients with multiple thymomas (2.5%) were treated with total thymectomy. One case in the Limited Thymectomy Group, which had been diagnosed as Masaoka stage II and WHO type B3 at initial surgery, recurred. None died of tumor progression in this study. Disease free survival rates at 10 years did not differ between the Limited Thymectomy and Total Thymectomy Groups (85.7% and 82.0%, respectively). There were no statistical differences in the incidence of postoperative myasthenia gravis and disease free survival between the two groups.
  
  
  CONCLUSIONS
  Resection of thymomas with surrounding tissue instead of total thymectomy can be indicated for stage I or II thymomas in light of disease free and overall survival, post-operative onset of MG, and the incidence of multiple lesions.
authors.affiliation: Department of Chest Surgery, Graduate School of Comprehensive Human Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Onuki
authors.forename: Shigemi
authors.initials: S
authors.lastname: Ishikawa
authors.forename: Kesato
authors.initials: K
authors.lastname: Iguchi
authors.forename: Yukinobu
authors.initials: Y
authors.lastname: Goto
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Sakai
authors.forename: Masaharu
authors.initials: M
authors.lastname: Inagaki
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Masataka
authors.initials: M
authors.lastname: Onizuka
authors.forename: Yukio
authors.initials: Y
authors.lastname: Sato
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ohara
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Sakakibara
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000209:etiology*; D009367:Neoplasm Staging; D011183:Postoperative Complications; D012189:Retrospective Studies; D016019:Survival Analysis; D013934:Thymectomy; D013945:Thymoma / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D013953:Thymus Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000601:surgery*