title: [Histopathological diagnosis of thyroid cancer in a multicenter trial].
abstract: BACKGROUND
  In the front of the problems related to the differentiation between benign and malignant thyroid tumors we decided to perform a multicentre study in order to validate diagnoses of malignant thyroid tumors and assess the inter-observer variability.
  
  
  METHODS
  Material included 690 cases of malignant and benign thyroid lesions with primary histopathology established in 1985-1999. These cases were selected to multicentre study. The studies were sent from centres which agreed to participate in the project and than coded in the independent centre--Department of Nuclear Medicine and Endocrine Oncology. 40 pathologists from 25 centres provided their diagnoses which were compared with the reference ones.
  
  
  RESULTS
  10 547 diagnoses were evaluated, both on their accuracy of the distinction between malignant and benign lesions and on their accuracy of cancer histotype definition. The reference diagnosis was made by an agreement between four expert pathologists (D.L., S.S., J.S. and A.K.). The participants diagnosed 21% of cases differently than experts. Concerning the diagnosis of cancer histotype, the difference between participants diagnosis and the reference one was even higher. The best concordance was achieved in the diagnosis of papillary thyroid cancer, however, on the cost of cancer overdiagnosis by some participants. Follicular cancer was diagnosed accurately only in 75.4% of cases.
  
  
  CONCLUSIONS
  The study documents a high inter-observer variability of thyroid cancer diagnosis and confirms the lesser accuracy of diagnosis of follicular cancer.
authors.affiliation: Comprehensive Cancer Center, MSC Memorial Institute, Gliwice Branch, Gliwice. dlange@io.gliwice.pl
authors.forename: Dariusz
authors.initials: D
authors.lastname: Lange
authors.forename: Stanisław
authors.initials: S
authors.lastname: Sporny
authors.forename: Jacek
authors.initials: J
authors.lastname: Sygut
authors.forename: Andrzej
authors.initials: A
authors.lastname: Kulig
authors.forename: Michał
authors.initials: M
authors.lastname: Jarzab
authors.forename: Dorota
authors.initials: D
authors.lastname: Kula
authors.forename: Barbara
authors.initials: B
authors.lastname: Jarzab
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000145:classification / Q000473:pathology*; D000236:Adenoma / Q000145:classification / Q000473:pathology*; D002291:Carcinoma, Papillary / Q000145:classification / Q000473:pathology*; D003937:Diagnosis, Differential; D006044:Goiter, Nodular / Q000145:classification / Q000473:pathology*; D006652:Histological Techniques / Q000379:methods / Q000592:standards; D006801:Humans; D015337:Multicenter Studies as Topic / Q000706:statistics & numerical data; D015588:Observer Variation; D013961:Thyroid Gland; D013964:Thyroid Neoplasms / Q000473:pathology*