Abstract
IMPORTANCE: Studies on the epidemiology of retinoblastoma (RB) could lead to improvement in management. OBJECTIVE: To estimate the incidence and survival of RB in European children and the occurrence of second primary tumors (other than RB) in these patients. DESIGN, SETTING, AND PARTICIPANTS: This cohort study used population-based data from 81 cancer registries in 31 European countries adhering to the European Cancer Registries (EUROCARE-6) project. Data collection took place between January 2000 and December 2013. European children aged 0 to 14 years diagnosed with RB were included. Data were analyzed from May to November 2023. EXPOSURES: Diagnosis of RB with International Classification of Diseases for Oncology, Third Edition (ICD-O-3), morphology coded 9510-9514 (retinoblastoma) and malignant behavior (fifth digit of morphology code, 3). MAIN OUTCOME AND MEASURES: Annual incidence (per million children aged 0-14 years), 5-year survival (%), and the standardized incidence ratio (SIR) of subsequent malignant neoplasms. RESULTS: The study included 3262 patients (mean [SD] age, 1.27 [1.63] years; 1706 [52%] male and 1556 [48%] female) from 81 registries. Of these, 3098 patients were considered in trend analysis after excluding registries with incomplete time coverage: 940 in 2000 to 2003, 703 in 2004 to 2006, 744 in 2007 to 2009, and 856 in 2010 to 2013. The estimated overall European incidence rate was 4.0 (95% CI, 3.9-4.1). Rates among countries varied from less than 2 million to greater than 6 million per year. No time trend of incidence was observed in any area. The overall European 5-year survival was 97.8% (95% CI, 95.5-98.9; 3180 cases). Five-year survival was lower in Estonia and Bulgaria (<80%) and 100% in several countries. Twenty-five subsequent malignant neoplasms were recorded during follow-up (up to 14 years), with an SIR of 8.2 and with cases occurring at mean ages between 1.3 and 8.9 years across different sites. An increased risk was found for hematological tumors (SIR, 5) and bone and soft tissue sarcomas (SIR, 29). CONCLUSIONS AND RELEVANCE: This study showed RB incidence remained stable at 4.0 per 1 000 000 European children aged 0 to 14 years from 2000 to 2013, but estimates varied among countries and differences in survival across countries persist. These data might be used to monitor RB management and occurrences of second tumors. The findings suggest future registry studies should aim to collect standardized RB stage at diagnosis and treatment to interpret disparities and potentially improve surveillance.