High-Risk Retinoblastoma Based on International Classification of Retinoblastoma: Analysis of 519 Enucleated Eyes

Purpose: To determine the correlation between the International Classification of Retinoblastoma (ICRB) and histopathologic high-risk retinoblastoma. Design: Retrospective study. Participants: A total of 519 patients. Intervention: Primary enucleation. Main Outcome Measures: High-risk retinoblastoma, metastasis, and death. Results: Of 519 primarily enucleated eyes, 87 (17%) were classified as group D and 432 (83%) were classified as group E on the basis of the ICRB. High-risk retinoblastoma was identified in 23% (117/519) of enucleated eyes, including 17% (15/87) group D and 24% (102/432) group E eyes. High-risk histopathologic features of retinoblastoma included anterior chamber involvement (5/15 [33%] group D eyes, 31/102 [30%] group E eyes), isolated massive posterior uveal invasion >= 3 mm (7/15 [47%] group D eyes, 22/102 [22%] group E eyes), isolated post-laminar optic nerve invasion (2/15 [13%] group D eyes, 46/102 [45%] group E eyes), and any combination of posterior uveal invasion and optic nerve involvement (7/15 [47%] group D eyes, 37/102 [36%] group E eyes). On logistic regression analysis, massive posterior uveal invasion >= 3 mm was more common in group D eyes (P = 0.0442), and post-laminar optic nerve invasion was more common in group E eyes (P = 0.0390). Of 117 patients with high-risk retinoblastoma, systemic adjuvant chemotherapy was administered in 83 patients (71%). Systemic metastasis developed in 0% (0/15) of those with high-risk group D retinoblastoma and 10% (10/102) of those with high-risk group E retinoblastoma over a mean follow-up period of 78 months (median, 62 months; range, 1-419 months). There was no metastasis in any patient (n = 402) classified with non-high-risk retinoblastoma. Of the 10 patients who developed metastasis, 4 had received prior adjuvant chemotherapy and 6 had no prior adjuvant chemotherapy. There was no metastasis in high-risk patients treated with vincristine sulphate, etoposide phosphate, and carboplatin (VEC). Death from metastasis occurred in 4% of high-risk patients (5/117). Conclusions: On the basis of the ICRB, 17% of group D and 24% of group E eyes are at increased risk for metastatic disease. In this study, 8% of patients developed metastasis. There was no metastasis in any patient classified with non-high-risk retinoblastoma.