Iodine-125 Plaque Radiotherapy for Retinoblastoma Recurrence Following Intra-arterial Chemotherapy

J Pediatr Ophthalmol Strabismus. 2022 May-Jun;59(3):164-171. doi: 10.3928/01913913-20210903-01. Epub 2021 Dec 20.

Abstract

Purpose: To assess the efficacy and toxicity of Iodine-125 (I-125) plaque radiotherapy for retinoblastoma following intra-arterial chemotherapy (IAC).

Methods: Clinical records of patients with retinoblastoma who received I-125 plaque radiotherapy after IAC at the Ocular Oncology Service at Wills Eye Hospital between December 1, 2009 and April 30, 2020, were retrospectively reviewed.

Results: Forty-one retinoblastomas in 41 eyes of 41 patients were treated with I-125 plaque radiotherapy after IAC at a median age of 32 months. The indication for plaque radiotherapy was solid tumor recurrence 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 and thickness was 9 and 4 mm, respectively. Mean radiation dose to tumor apex was 3,483 centigray (cGy) delivered at mean rate of 35 cGy/hr. The irradiated site was controlled in 39 eyes (95%) at a median of 20 months after plaque radiotherapy for solid tumor (31 of 33, 94%), subretinal (6 of 6,100%), and vitreous seeds (2 of 2, 100%). A subgroup of tumors occurring within an ischemic retinal/choroidal field was identified on fluorescein angiography (n = 24) and demonstrated control in 22 of 24 (92%). Using Kaplan-Meier analysis, radiation complications at 2 years included vitreous hemorrhage (37%), retinopathy (28%), papillopathy (18%), and cataract (18%). Five eyes (12%) were enucleated for recurrence outside the irradiated area, chronic vitreous hemorrhage, and/or total retinal detachment.

Conclusions: Iodine-125 plaque radiotherapy provided 95% control for retinoblastoma tumors that failed IAC, including those in ischemic fields untreatable with further chemotherapy. Radiation complications should be anticipated in eyes exposed to substantial chemotherapy. [J Pediatr Ophthalmol Strabismus. 2022;59(3):164-171.].

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use
  • Child, Preschool
  • Humans
  • Infant
  • Infusions, Intra-Arterial
  • Iodine Radioisotopes / therapeutic use
  • Retina / pathology
  • Retinal Neoplasms* / diagnosis
  • Retinal Neoplasms* / drug therapy
  • Retinoblastoma* / diagnosis
  • Retinoblastoma* / drug therapy
  • Retrospective Studies
  • Treatment Outcome
  • Vitreous Hemorrhage / drug therapy

Substances

  • Iodine Radioisotopes
  • Iodine-125