Abstract
Purpose :
To assess the efficacy and toxicity of Iodine-125 (I-125) plaque radiotherapy for residual or recurrent retinoblastoma following intra-arterial chemotherapy (IAC).
Methods :
In a retrospective review, clinical records of all children with retinoblastoma that received I-125 plaque radiotherapy after IAC on the Ocular Oncology Service at Wills Eye Hospital between December 1, 2009 and April 30, 2020 were reviewed.
Results :
There were 41 retinoblastomas in 41 eyes of 41 patients treated with I-125 plaque radiotherapy after IAC, including 21 females (51%) and 20 males (49%) with a median age at plaque treatment of 32 months (range 9-71 months). The most common indication for I-125 plaque radiotherapy was recurrence of solid tumor with or without overlying subretinal/vitreous seeds (n=33, 80%), subretinal seeds alone (n=6, 15%), and vitreous seeds alone (n=2, 5%). The median irradiated basal diameter was 9 millimeters (mm) (range 2-16 mm) and median thickness was 4 mm (range 1-7 mm). Mean radiation dose to tumor apex was 3483 centigray. There was complete tumor control at the target site in 39 eyes (95%) at median follow-up of 20 months (range 1-109 months) after plaque radiotherapy. This included control within the target site for solid tumor (31/33, 94%), subretinal seeds (6/6,100%), and vitreous seeds (2/2, 100%). A subgroup of solid tumor and/or subretinal seeds was identified, which occurred within an ischemic retinal/choroidal field, confirmed on fluorescein angiography and associated with highly calcified mass (n=24 cases). This select group demonstrated tumor control in 22/24 (92%). Visual acuity at last follow-up was ‘fix and follow’ in 13/14 (93%) of pre-verbal patients and 20/400 or better in 10/22 (45%) of verbal patients. Using Kaplan-Meier analysis, radiation complications at 2 years included vitreous hemorrhage (37%), retinopathy (28%), papillopathy (18%), and cataract (18%). Enucleation was necessary in 5 eyes (12%) for recurrence outside of the irradiated area, chronic vitreous hemorrhage, and/or total retinal detachment.
Conclusions :
In this analysis, Iodine-125 plaque radiotherapy provided 95% tumor control for selected retinoblastomas that failed IAC, including those in an ischemic field, untreatable with further chemotherapy. Radiation-related side effects should be anticipated in these eyes already exposed to substantial chemotherapy.
This is a 2021 ARVO Annual Meeting abstract.