title: Rare cancers in The Netherlands: a population-based study.
abstract: The conventional definition for rare disease is based on prevalence. Because of differences in prognosis, a definition on the basis of incidence was deemed to be more appropriate for rare cancers. Within the European RARECARE project, a definition was introduced that defines cancers as rare when the crude incidence rate is less than six per 100 000 per year. In this study, we applied the RARECARE definition for rare cancer to the Netherlands; this to identify the usefulness of the definition in a single country and to provide more insight into the burden of rare cancers in the Netherlands. Data for 2004 through 2008 were extracted from the Netherlands Cancer Registry and classified according to the RARECARE entities (tumour groupings). Crude and European standardized incidence rates were calculated. Out of the 260 entities, 223 (86%) were rare according to the definition, accounting for 14 000 cancers (17% of all). Considerable fluctuations in crude rates over years were observed for the major group of cancers. Rare tumours in the Netherlands constituted 17% of all newly diagnosed tumours, but were divided over 223 different entities, indicating the challenge that faces clinicians. To make the definition of rare cancers better applicable, it should be refined by taking into consideration the sex-specific incidence for sex-specific cancer sites. Moreover, a mean incidence over 5 years will provide more solid insight into the burden, eliminating large fluctuations in time of most of the cancers.
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, Utrecht.
authors.forename: Jan M
authors.initials: JM
authors.lastname: van der Zwan
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, Utrecht.|Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen.
authors.forename: Boukje A C
authors.initials: BAC
authors.lastname: van Dijk
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, Utrecht.
authors.forename: Otto
authors.initials: O
authors.lastname: Visser
authors.affiliation: Department of Pathology, Radboud University Nijmegen Medical Centre, Nijmegen.
authors.forename: Han J H J M
authors.initials: HJHJM
authors.lastname: van Krieken
authors.affiliation: Department of Cancer Epidemiology, Istituto Superiore di Sanita, Rome, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Capocaccia
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, Utrecht.|Department of HTSR, MIRA institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, the Netherlands.
authors.forename: Sabine
authors.initials: S
authors.lastname: Siesling
mesh_terms: D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D009369:Neoplasms / Q000453:epidemiology*; D009426:Netherlands / Q000453:epidemiology; D011379:Prognosis; D035583:Rare Diseases / Q000453:epidemiology*; D012042:Registries / Q000706:statistics & numerical data*