Ocular Survival Following Intravitreal Melphalan as Adjuvant Treatment for Vitreous Retinoblastoma Seeding

PURPOSE: To evaluate the efficacy of intravitreal chemotherapy for vitreous seeding in patients with retinoblastoma (Rb). DESIGN: Retrospective, single-arm cohort study. METHODS: This study was conducted at a tertiary eye center. Between 2013 and 2021, 27 patients (27 eyes) with vitreous Rb receiving adjuvant intravitreal melphalan (IVM) as secondary/salvage treatment in one eye were included. Patients who were unable to follow-up or treated elsewhere were excluded. Survival analysis was performed to assess the incidence of enucleation in the melphalan-treated group, as well as in bilateral cases with eyes receiving melphalan and those receiving standard treatment, consisting of chemotherapy, thermotherapy, and enucleation according to the disease stage. RESULTS: The median (interquartile range) follow-up time was 65 months (range, 34–83 months). Seventeen patients (63%) had bilateral disease. Sixteen eyes (59%) were saved. The Kaplan–Meier survival estimates for eyes receiving melphalan were 100% at 1 year (95% confidence interval [CI]:11.2–14.3), 75% (95% CI:14.2–48.9) at 3 years, and 50% at 5 years. Melphalan-treated patients with bilateral disease showed a significantly higher number of saved eyes than the standard treatment group (P=0.002). Tumor recurrence was the primary cause of enucleation, accounting for 36% of the cases. In the vitreous hemorrhage group, the odds of enucleation were 13 times higher (95% CI:1.04–165.28) than in the group without this condition. CONCLUSION: IVM is an effective treatment option for vitreous seeds. After 3 years of follow-up, the estimated survival rate for saved eyes decreased, and vitreous hemorrhage significantly increased the likelihood of enucleation. Further studies are required to determine the precise effects of IVM.