To investigate on the safety and efficacy of intravitreous chemotherapy for retinoblastoma seeding in a relatively large cohort and provide information on the necessary number of injections and long-term control.Methods:
Retrospective interventional case series of 40 consecutive eyes with viable vitreous seeding after standard treatment of retinoblastoma. All eyes received intravitreal melphalan injection (20–30 μg) and additional topotecan (20 μg) as needed using the trans pars plana route with triple freeze–thaw cryotherapy at needle withdrawal for prevention of extraocular seeding for planned six cycles.Results:
The mean patient age at presentation was 36 months, and interval to need for vitreous injection was 14 months. Viable vitreous (n = 40 eyes) and additional subretinal (n = 2 eyes) seeds were documented. There was a total of 192 injections using melphalan (n = 148) and/or topotecan (n = 44) with mean number of injections per eye of melphalan at 4 (median, 4; range, 1–6) and topotecan at 3 (median, 3; range, 1–5). Fewer than six planned melphalan injections (n = 31 cases, 78%) were necessary because of rapid and complete vitreous seed control (n = 30 eyes) or melphalan allergy (n = 1 eye). Fewer than six planned topotecan injections (n = 14 cases, 100%) were necessary because of rapid and complete vitreous seed control in all cases. At median 3-year follow-up, therapeutic success with continued seed regression was observed in all 40 eyes (100%). Globe salvage was attained in 35 cases (88%), and enucleation (n = 5) was necessary for extensive recurrent subretinal seeds (n = 2), neovascular glaucoma with vitreous hemorrhage (n = 2), and hemorrhagic retinal necrosis (n = 1). Side effects included focal retinal pigment epithelial mottling at the site of injection (n = 12), minor focal paraxial lens opacity (not requiring cataract surgery) (n = 11), transient focal vitreous hemorrhage (n = 5), transient hypotony (n = 3), transient retinal hemorrhage (n = 2), optic disc edema (n = 1), and hemorrhagic retinal necrosis (n = 1). There was no case of endophthalmitis, extraocular tumor extension, metastasis, or death.Conclusion:
Intravitreal melphalan and/or topotecan injection for retinoblastoma vitreous seeding provides lasting tumor control at 3 years with approximately 4 injections.