Retinoblastoma with and without Extraocular Tumor Extension: A Global Comparative Study of 3435 Patients.

PURPOSE

To 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).

DESIGN

Multicenter intercontinental collaborative prospective study from 2017 to 2020. RB-EOE cases included those with overt orbital tumor extension in treatment-naive patients. Cases with microscopic orbital extension detected postenucleation were excluded from the study.

PARTICIPANTS

A total of 319 children with RB-EOE and 3116 children with RB-w/o-EOE.

INTERVENTION

Chemotherapy, enucleation, exenteration, radiotherapy.

MAIN OUTCOME MEASURES

Systemic metastasis and death.

RESULTS

Of the 3435 RB patients included in this study, 309 (9%) were from low-income countries (LIC), 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 LIC, 197 (6%) lower-middle income, 20 (2%) upper-middle income, and 6 (1%) patients from high-income countries ( = 0.0001). The outcomes were statistically significant for RB-EOE compared with RB-w/o-EOE: systemic metastasis (32% vs. 4% respectively;  = 0.0001) and metastasis-related death (63% vs. 6% respectively;  = 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 (EBRT) 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 of death from RB-EOE was greater in patients aged >4 years than <2 years (hazard ratio, 2.912; < 0.001) and for unimodal (surgery or intravenous chemotherapy) and bimodal (surgery and intravenous chemotherapy) treatment than trimodal treatment (surgery, intravenous chemotherapy, and EBRT) (hazard ratio, 2.023;  = 0.004 and hazard ratio, 1.819;  = 0.027, respectively).

CONCLUSIONS

Retinoblastoma with extraocular tumor extension is associated with a higher risk of metastasis and death. Patients with RB-EOE are likely to benefit from trimodal treatment (intravenous chemotherapy, surgery, and EBRT) rather than treatment protocols excluding EBRT.

FINANCIAL DISCLOSURES

The authors have no proprietary or commercial interest in any materials discussed in this article.