PurposeTo study the treatment, and outcomes of children with retinoblastoma (RB) with extraocular tumor extension (RB-EOE) and compare them with RB without extraocular tumor extension (RB-w/o-EOE). DesignMulticenter intercontinental collaborative prospective study from 2017 to 2020. RB-EOE cases included those with overt orbital tumor extension in treatment-naïve patients. Cases with microscopic orbital extension detected post-enucleation were excluded from the study. ParticipantsA total of 319 children with RB-EOE and 3116 children with RB-w/o-EOE Intervention(s)Chemotherapy, enucleation, exenteration, radiotherapy. Main outcomes(s)Systemic metastasis and death. ResultsOf the 3435 RB patients included in this study, 309 (9%) were from low-income countries, 1448 (42%) from lower-middle income, 1012 (29%) from upper-middle income, and 666 (19%) patients from high-income countries. There was an inverse relationship between the percentage of RB-EOE and national income level, with 96 (31%) patients from low-income countries, 197 (6%) lower middle-income, 20 (2%) upper-middle income, and 6 (1%) patients from high-income countries (p=0.0001). The outcomes were statistically significant for RB-EOE compared to RB-w/o-EOE: systemic metastasis (32% vs 4% respectively; p=0.0001) and metastasis-related death (63% vs 6% respectively; p=0.0001). Multimodal treatment was the most common form of treatment (n=177; 54%) for RB-EOE, with most cases undergoing a combination of intravenous chemotherapy and enucleation (n=97; 30%). Adjuvant external beam radiotherapy after surgery (enucleation/orbital exenteration) was given in only 68 (21%) cases. Kaplan-Meier analysis for systemic metastasis and metastasis-related death in RB-EOE was 28% and 57% at 1 year, 29% and 60% at 2 years, and 29% and 61% at 3 years, respectively. Cox regression analysis revealed that the risk for death from RB-EOE was greater in patients aged >4 years than <2 years (hazard ratio (HR)=2.912; p<0.001) and for unimodal (surgery or intravenous chemotherapy) and bimodal (surgery and intravenous chemotherapy) treatment than trimodal treatment (surgery, intravenous chemotherapy and external beam radiotherapy) (HR=2.023; p=0.004 and HR 1.819; p=0.027 respectively). ConclusionRetinoblastoma with extraocular tumor extension is associated with a higher risk for metastasis and death. Patients with RB-EOE are likely to benefit from trimodal treatment (intravenous chemotherapy, surgery, and external beam radiotherapy) rather than treatment protocols excluding external beam radiotherapy.
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