title: Prognosis of thymic epithelial tumors according to the new World Health Organization histologic classification.
abstract: BACKGROUND
  The aim of this study was to document the prognosis of thymic epithelial tumors (TETs) according to new the World Health Organization (WHO) classification.
  
  
  METHODS
  We retrospectively reviewed 150 patients with TETs that were confirmed pathologically during 11 years (from 1992 to 2002) in Severance Hospital, Seoul, Korea.
  
  
  RESULTS
  TETs were classified as type A, AB, B1, B2, B3, or C, tumors and these represented 7 (4.7%), 26 (17.3%), 13 (8.7%), 45 (30.0%), 26 (17.3%), and 33 (22.0%) cases, and the 5-year survival rates were 100%, 93%, 89%, 82%, 71%, and 23%, respectively. Their Masaoka stages were I, II, III, IVa, and IVb, with 53 (35.3%), 39 (26.0%), 20 (13.3%), 22 (14.7%), and 16 (10.7%) cases. Tumor invasiveness, recurrence, completeness of resection, and tumor-related death were more frequent in types AB, B2, B3, and C than in types A and B1. Multivariate analysis showed that Masaoka stage (p < 0.001) and the WHO classification (p = 0.019) were significant independent prognostic factors.
  
  
  CONCLUSIONS
  The WHO classification is associated with tumor invasiveness, recurrence, completeness of resection, and tumor-related death, and has good correlation with Masaoka stage. The WHO histologic subtypes are an independently significant prognostic factor with respect to survival in our multivariate analysis. Types AB, B2, B3, and C showed invasive behaviors and R1 or R2 resections were frequently performed. Postoperative adjuvant radiotherapy was effective, but long-term follow-up is recommended because of decreased survival after 5 years following operation. The WHO classification may be helpful in clinical practice for the assessment and treatment of TET patients.
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Moo Suk
authors.initials: MS
authors.lastname: Park
authors.forename: Kyung Young
authors.initials: KY
authors.lastname: Chung
authors.forename: Kil Dong
authors.initials: KD
authors.lastname: Kim
authors.forename: Woo Ick
authors.initials: WI
authors.lastname: Yang
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Chung
authors.forename: Young Sam
authors.initials: YS
authors.lastname: Kim
authors.forename: Joon
authors.initials: J
authors.lastname: Chang
authors.forename: Joo Hang
authors.initials: JH
authors.lastname: Kim
authors.forename: Sung Kyu
authors.initials: SK
authors.lastname: Kim
authors.forename: Se Kyu
authors.initials: SK
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D013945:Thymoma / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000556:secondary / Q000628:therapy*; D013953:Thymus Neoplasms / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000628:therapy*; D014944:World Health Organization