title: The impact of thymoma histotype on prognosis in a worldwide database.
abstract: BACKGROUND
  The rarity of thymomas and lack of multi-institutional studies have hampered therapeutic progress for decades. To overcome this, the members of the International Thymic Malignancy Interest Group created a worldwide retrospective database. This database was analyzed regarding the demographic and geographic distribution of thymomas and the impact of different variables on survival and recurrence.
  
  
  METHODS
  This study analyzed 4221 thymomas diagnosed between 1983 and 2012 with World Health Organization histotype information from the International Thymic Malignancy Interest Group database. Associations to survival and recurrence were studied by univariate and multivariate analyses.
  
  
  RESULTS
  Type B2 thymoma is the most common (28%) and type A the least common (12%) histotypes. They are significantly more frequent in Europe and the United States than Asia. Type A and AB occur at significantly higher age than other thymomas (64 and 57 years, respectively). There are no differences in gender distribution. Stage is lower in type A (90% in stages I-II) and AB than B1 to B3 thymomas (38% of type B3 in stage III). In univariate analysis, recurrence is significantly less frequent among stage I/II tumors, in type A and AB (recurrence rates, 1-2%) than B1 to B3 thymomas (2-7%). Multivariate analysis reveals an impact of age, stage, and resection status on survival and recurrence, whereas for histology there is only a significant impact on recurrence.
  
  
  CONCLUSIONS
  New findings are (1) geographic differences such as a lower incidence of type A and B2 thymoma in Asia; and (2) impact of stage and histology, the latter partially limited to early stage disease, on recurrence.
authors.affiliation: *Institute of Pathology, University Medical Centre Mannheim, University of Heidelberg, Mannheim, Germany; †Section of Medical Oncology, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut; ‡Division of Thoracic Surgery, Department of Surgery, Yale University School of Medicine, New Haven, Connecticut; §Department of Pathology, Regina Elena National Cancer Institute, Rome, Italy; ║Department of Histopathology, Royal Brompton Hospital, and National Heart and Lung Institute, Imperial College London, London, United Kingdom; ¶Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York; and #Institute of Pathology, University Medical Center Göttingen, University of Göttingen, Göttingen, Germany.
authors.forename: Cleo-Aron
authors.initials: CA
authors.lastname: Weis
authors.forename: Xiaopan
authors.initials: X
authors.lastname: Yao
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Deng
authors.forename: Frank C
authors.initials: FC
authors.lastname: Detterbeck
authors.forename: Mirella
authors.initials: M
authors.lastname: Marino
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Nicholson
authors.forename: James
authors.initials: J
authors.lastname: Huang
authors.forename: Philipp
authors.initials: P
authors.lastname: Ströbel
authors.forename: Alberto
authors.initials: A
authors.lastname: Antonicelli
authors.forename: Alexander
authors.initials: A
authors.lastname: Marx
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016019:Survival Analysis; D013945:Thymoma / Q000453:epidemiology* / Q000473:pathology*; D016896:Treatment Outcome; D014944:World Health Organization