Outcomes of Intravenous Chemotherapy (Chemoreduction) for Retinoblastoma Based on Patient Age in 964 Eyes of 554 Patients

Purpose: To evaluate retinoblastoma control after intravenous chemotherapy (chemoreduction) by patient age at presentation. Design: Retrospective case series. Methods: This study included 964 eyes of 554 patients treated with chemoreduction at Ocular Oncology Service at Wills Eye Hospital. Patients received 6 monthly cycles of standard chemoreduction. Additional therapies for tumor control were performed as needed. Results: Of 964 eyes, a comparison by age group (<6 months vs. 6-12 months vs. 13-24 months vs. >24 months) revealed more advanced age group with higher frequency of group E tumor (15% vs. 25% vs. 32% vs. 39%, P<0.001). By treatment outcomes, complete tumor control was achieved with chemoreduction alone more often in less advanced age group (46% vs. 30% vs. 17% vs. 8%, P<0.001). Additional treatment after chemoreduction was needed more often in more advanced age group with external beam radiotherapy (EBRT; 9% vs. 16% vs. 20% vs. 15%, P=0.006) or enucleation (12% vs. 18% vs. 26% vs. 37%, P<0.001). Over time (1994-1998 vs. 1999-2003 vs. 2004-2008 vs. 2009-2013 vs. 2014-2019), the paradigm for additional required treatment after chemoreduction shifted toward less EBRT (27% vs. 24% vs. 14% vs. 7% vs. 2%, P<0.001) and more intra-arterial (0% vs. 0% vs. 1% vs. 25% vs. 48%, P<0.001) and intravitreal (0% vs. 0% vs. 3% vs. 10% vs. 20%, P<0.001) chemotherapy. Conclusions: Chemoreduction is a safe and effective treatment method for patients with retinoblastoma, demonstrating the best tumor control in the younger age groups.