title: Data quality in rare cancers registration: the report of the RARECARE data quality study.
abstract: OBJECTIVE
  Rare cancers represent 22% of all tumors in Europe; however, the quality of the data of rare cancers may not be as good as the quality of data for common cancer. The project surveillance of rare cancers in Europe (RARECARE) had, among others, the objective of assessing rare cancer data quality in population-based cancer registries (CRs). Eight rare cancers were considered: mesothelioma, liver angiosarcoma, sarcomas, tumors of oral cavity, CNS tumors, germ cell tumors, leukemia, and malignant digestive endocrine tumors.
  
  
  METHODS
  We selected data on 18,000 diagnoses and revised, on the basis of the pathologic and clinical reports (but not on pathologic specimens), unspecified morphology and topography codes originally attributed by CR officers and checked the quality of follow-up of long-term survivors of poor prognosis cancers.
  
  
  RESULTS
  A total of 38 CRs contributed from 13 European countries. The majority of unspecified morphology and topography cases were confirmed as unspecified. The few unspecified cases that, after the review, changed to a more specific diagnosis increased the incidence of the common cancer histotypes. For example, 11% of the oral cavity epithelial cancers were reclassified from unspecified to more specific diagnoses: 8% were reclassified as squamous cell carcinoma (commoner) and only 1% as adenocarcinoma (rarer). The revision confirmed the majority of long-term survivors revealing a relative high proportion of mesothelioma long-term survivors. The majority of appendix carcinoids changed behavior from malignant to borderline lesions.
  
  
  CONCLUSIONS
  Our study suggests that the problem of poorly specified morphology and topography cases is mainly one of difficulty in reaching a precise diagnosis. The awareness of the importance of data quality for rare cancers should increase among registrars, pathologists, and clinicians.
authors.affiliation:  Evaluative Epidemiology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan - Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Trama
authors.affiliation:  Epidemiology Unit and Girona Cancer Registry, Oncology Coordination Plan, Department of Health, Girona Biomedical Research Institute, Girona - Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Marcos-Gragera
authors.affiliation:  Escuela Andaluza de Salud Pública. Instituto de Investigación Biosanitaria ibs.GRANADA. Hospitales Universitarios de Granada/Universidad de Granada, Granada - Spain.| CIBER de Epidemiología y Salud Pública (CIBERESP) - Spain.
authors.forename: Maria Josè
authors.initials: MJ
authors.lastname: Sánchez Pérez
authors.affiliation:  Department of Research, Comprehensive Cancer Centre The Netherlands, Utrecht - The Netherlands.
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van der Zwan
authors.affiliation:  CIBER de Epidemiología y Salud Pública (CIBERESP) - Spain.| Instituto de Salud Pública de Navarra, Pamplona - Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Ardanaz
authors.affiliation:  Geneva Cancer Registry, Institute of Global Health, Faculty of Medicine, University of Geneva, Geneva - Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Bouchardy
authors.affiliation:  Escuela Andaluza de Salud Pública. Instituto de Investigación Biosanitaria ibs.GRANADA. Hospitales Universitarios de Granada/Universidad de Granada, Granada - Spain.
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: Melchor
authors.affiliation:  Escuela Andaluza de Salud Pública. Instituto de Investigación Biosanitaria ibs.GRANADA. Hospitales Universitarios de Granada/Universidad de Granada, Granada - Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Martinez
authors.affiliation:  Centro Nazionale di Epidemiologia, Sorveglianza e Promozione della Salute (CNESPS), Istituto Superiore di Sanità, Rome - Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Capocaccia
authors.affiliation:  Servizio Interaziendale di Epidemiologia, Azienda Unità Sanitaria Locale and IRCCS, Arcispedale Santa Maria Nuova, Reggio Emilia - Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Vicentini
authors.affiliation:  Department of Research, Comprehensive Cancer Centre The Netherlands, Utrecht - The Netherlands.| Department of Health Technology and services research, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede - The Netherlands.
authors.forename: Sabine
authors.initials: S
authors.lastname: Siesling
authors.affiliation:  Evaluative Epidemiology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan - Italy.
authors.forename: Gemma
authors.initials: G
authors.lastname: Gatta
mesh_terms: D000068598:Data Accuracy; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000453:epidemiology*; D035583:Rare Diseases / Q000453:epidemiology*; D012042:Registries