Rare cancers are not so rare: the rare cancer burden in Europe.
There is no internationally agreed definition of a rare cancer. In Europe, rare diseases are often defined as those with a prevalence of <50/100,000 . In the US, the Orphan Drug Designation Program defines rare diseases as those affecting <200,000 people in the total US population, equivalent to a prevalence of 64/100,000 . The problem with both these definitions is that they are based on prevalence, which does not properly reflect the health burden of incident diseases such as cancer. RARECARE more usefully defines rare cancers as those with an incidence of <6/100,000/year . Using this definition, the combined annual incidence rate of all rare cancers in Europe is about 108 per 100,000, corresponding to 541,000 new diagnoses annually or 22% of all cancer diagnoses. This is more than any single common cancer. And returning to prevalence, about 4,300,000 patients are living today in the European Union with a diagnosis of a rare cancer, 24% of the total cancer prevalence.