Characterization of the Portuguese population diagnosed with retinoblastoma

The purpose of this study is to characterize demographically and genetically the Portuguese population with retinoblastoma; to report the clinical stage at presentation and its impact on survival and ocular preservation rate and, finally, to assess the incidence of retinoblastoma in Portugal. Retrospective observational study including children consecutively diagnosed with retinoblastoma at the Portuguese National Referral Center of Intraocular Tumors, between October 2015 and October 2020. Twenty-eight children were diagnosed with retinoblastoma at our center, 15 hereditary from which 12 presented with bilateral retinoblastoma and 3 were unilateral. The overall mean age at diagnosis was 13.6 ± 11.1 months with hereditary retinoblastomas diagnosed slightly earlier at 9.6 ± 6.3 months. A familial history of retinoblastoma was found in only 4 (14.3%) of the cases. A pathogenic mutation in the RB1 gene was found in 13 (46.4%) of the children. The most frequent sign at referral was leukocoria in 71.4% of patients. Considering the ICRB classification of the tumors, 84.6% of non-hereditable hereditary retinoblastomas were referred to our center in advanced stages. In the group of hereditable retinoblastomas 86.7% presented with one of the eyes with advanced intraocular retinoblastoma. Fourteen children had one eye enucleated due to retinoblastoma. No deaths were registered during the study period. Considering the incidence analysis, we registered a year-of-birth controlled incidence analysis of 4.04 per 100.000 living births (IC 95% 1.59-6.49). This is the first characterization of the Portuguese Population diagnosed with Retinoblastoma in the National Reference Center.