Rare cancers in The Netherlands: a population-based study

Area of Science:

• Oncology
• Epidemiology
• Public Health

Background:

• Rare diseases are conventionally defined by prevalence.
• Rare cancers require a definition based on incidence due to prognostic differences.
• The European RARECARE project proposed a definition for rare cancers based on incidence rates.

Purpose of the Study:

• To assess the utility of the RARECARE definition for rare cancers in the Netherlands.
• To determine the burden of rare cancers within a single country.
• To provide insights into the epidemiological characteristics of rare cancers in the Netherlands.

Main Methods:

• Utilized data from the Netherlands Cancer Registry (2004-2008).
• Classified cancers according to RARECARE entities (tumor groupings).
• Calculated crude and European standardized incidence rates.

Main Results:

• 223 out of 260 (86%) entities met the RARECARE definition for rare cancers.
• Rare cancers accounted for 14,000 diagnoses, representing 17% of all cancers.
• Significant yearly fluctuations in crude incidence rates were observed for major cancer groups.

Conclusions:

• The RARECARE definition is applicable in the Netherlands, identifying a substantial proportion of rare cancers.
• The high number of rare cancer entities (223) presents diagnostic and treatment challenges for clinicians.
• Refining the definition with sex-specific incidence and 5-year mean rates is recommended for better applicability and burden assessment.