title: The burden of rare cancer in Japan: application of the RARECARE definition.
abstract: BACKGROUND
  Despite the fact that rare cancer is a new target of cancer control in Japan, the incidence of rare cancers is unknown and there is no generally accepted definition of rare cancers in this country. With the aim of calculating incidences of rare cancers in Japan, we therefore adopted a definition and classification of rare cancers that had been published in the European Union (EU) in 2011.
  
  
  METHODS
  Using incidence data between 1998 and 2007 submitted by 12 of population based cancer registries in Japan that met our quality criteria and drawing on the EU definition (incidence <6 per 100,000 per year), we estimated the incidences of 845 combinations of tumor sites and histological groups and thus identified the cancers that are rare in Japan.
  
  
  RESULTS
  After identifying 193 combinations of tumor sites and histological groups that fit our criteria for rare cancers, we estimated their incidence to be about 75 per 100,000, which corresponds to about 94,800 new diagnoses in 2012 or approximately 15% of all cancer diagnoses. The categorization of rare and common cancers was almost the same in Japan as in EU.
  
  
  CONCLUSIONS
  The present study provides an indication of the size of the rare cancer burden in Japan and epidemiological information to explore this. We are expecting further discussion based on our results with stakeholders in order to construct a Japanese definition of rare cancers.
authors.affiliation: Department of Mathematical Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita 565-0871, Osaka, Japan. Electronic address: tamaki.tomoko.73e@st.kyoto-u.ac.jp.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tamaki
authors.affiliation: Department of Mathematical Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita 565-0871, Osaka, Japan. Electronic address: luckyer.tou17@sahs.med.osaka-u.ac.jp.
authors.forename: Yiqi
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Mathematical Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita 565-0871, Osaka, Japan. Electronic address: ohno@sahs.med.osaka-u.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ohno
authors.affiliation: Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita 565-0871, Osaka, Japan. Electronic address: tsobue@envi.med.osaka-u.ac.jp.
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Sobue
authors.affiliation: Division of Surveillance, Center for Cancer Control and Information Services, National Cancer Center, 5-1-1 Tsukiji Chuo-ku, Tokyo 104-0045, Japan. Electronic address: hnishimo@ncc.go.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishimoto
authors.affiliation: Division of Surveillance, Center for Cancer Control and Information Services, National Cancer Center, 5-1-1 Tsukiji Chuo-ku, Tokyo 104-0045, Japan. Electronic address: akshibat@ncc.go.jp.
authors.forename: Akiko
authors.initials: A
authors.lastname: Shibata
mesh_terms: D017281:Cost of Illness; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D009369:Neoplasms / Q000453:epidemiology* / Q000473:pathology; D035583:Rare Diseases / Q000453:epidemiology* / Q000473:pathology
keywords: Cancer registries; Incidence; Population-based; Rare cancers