Adjuvant therapy for children treated by enucleation at diagnosis of retinoblastoma

Introduction Advanced localized retinoblastoma can be cured by enucleation, but extraocular spread of retinoblastoma cells is associated with a high mortality. Risk-stratified adjuvant treatment with chemotherapy and radiotherapy has been shown to reduce the risk for extraocular relapse in children with histopathological risk factors. Methods Data of 184 patients with retinoblastoma and primary enucleation were collected in a prospective, multicenter, observational study between 2013 and 2020. The clinical characteristics were evaluated as risk factors and progression-free and overall survival rates were compared. Results Seventy-one percent of 184 children with retinoblastoma treated with primary enucleation were diagnosed with low risk histopathological factors (pT1/pT2a) and received no adjuvant therapy. Children with intermediate risk (pT2b,pT3; 48 children, 26.0%) and high risk for metastasis (pT4; 5 children, 2.7%) received risk-stratified adjuvant treatment. None of the children with low risk or intermediate risk (pT1-pT3) relapsed, but two of five children with high-risk retinoblastoma (pT4) developed extraocular relapses and one deceased. The 2-year progression-free survival rate and 2-year overall survival rate was 100% for children with pT1-3 retinoblastoma. However, the 2-year progression-free survival rate and 2-year overall survival rate for children with pT4 was statistically notably reduced with 2 of 5 children developing progression and 1 death among the 5 children within 2 years after diagnosis. Conclusion Primary enucleation alone and with additional risk-stratified adjuvant chemotherapy treatment provides high cure rates in patients with pT1-3 retinoblastoma, but children with pT4 retinoblastoma remain at high risk to develop extraocular retinoblastoma. International prospective clinical trials are required to evaluate reduction of intensity of adjuvant chemotherapy in some risk groups (pT2, pT3) and intensification for pT4 retinoblastoma

Introduction of a Variant Classification System for Analysis of Genotype-Phenotype Relationships in Heritable Retinoblastoma

Constitutional haploinsufficiency of the RB1 gene causes heritable retinoblastoma, a tumor predisposition syndrome. Patients with heritable retinoblastoma develop multiple retinoblastomas early in childhood and other extraocular tumors later in life. Constitutional pathogenic variants in RB1 are heterogeneous, and a few genotype-phenotype correlations have been described. To identify further genotype-phenotype relationships, we developed the retinoblastoma variant effect classification (REC), which considers each variant’s predicted effects on the common causal mediator, RB1 protein pRB. For validation, the RB1 variants of 287 patients were grouped according to REC. Multiple aspects of phenotypic expression were analyzed, known genotype-phenotype associations were revised, and new relationships were explored. Phenotypic expression of patients with REC-I, -II, and -III was distinct. Remarkably, the phenotype of patients with variants causing residual amounts of truncated pRB (REC-I) was more severe than patients with complete loss of RB1 (REC-II). The age of diagnosis of REC-I variants appeared to be distinct depending on truncation’s localization relative to pRB structure domains. REC classes identify genotype-phenotype relationships and, therefore, this classification framework may serve as a tool to develop tailored tumor screening programs depending on the type of RB1 variant