Background Rare cancers pose challenges for diagnosis, treatments, and clinical decision making. Information about rarecancers is scant. The RARECARE project defined rare cancers as those with an annual incidence of less than six per100 000 people in European Union (EU). We updated the estimates of the burden of rare cancers in Europe, their timetrends in incidence and survival, and provide information about centralisation of treatments in seven European countries.Methods We analysed data from 94 cancer registries for more than 2 million rare cancer diagnoses, to estimateEuropean incidence and survival in 2000–07 and the corresponding time trends during 1995–2007. Incidence wascalculated as the number of new cases divided by the corresponding total person-years in the population. 5-yearrelative survival was calculated by the Ederer-2 method. Seven registries (Belgium, Bulgaria, Finland, Ireland, theNetherlands, Slovenia, and the Navarra region in Spain) provided additional data for hospitals treating about220 000 cases diagnosed in 2000–07. We also calculated hospital volume admission as the number of treatmentsprovided by each hospital rare cancer group sharing the same referral pattern.Findings Rare cancers accounted for 24% of all cancers diagnosed in the EU during 2000–07. The overall incidencerose annually by 0.5% (99·8% CI 0·3–0·8). 5-year relative survival for all rare cancers was 48·5% (95% CI 48·4 to 48·6),compared with 63·4% (95% CI 63·3 to 63·4) for all common cancers. 5-year relative survival increased (overall 2·9%,95% CI 2·7 to 3·2), from 1999–2001 to 2007–09, and for most rare cancers, with the largest increases for haematologicaltumours and sarcomas. The amount of centralisation of rare cancer treatment varied widely between cancers andbetween countries. The Netherlands and Slovenia had the highest treatment volumes.Interpretation Our study benefits from the largest pool of population-based registries to estimate incidence andsurvival of about 200 rare cancers. Incidence trends can be explained by changes in known risk factors, improveddiagnosis, and registration problems. Survival could be improved by early diagnosis, new treatments, and improvedcase management. The centralisation of treatment could be improved in the seven European countries we studied.