Applications of Iodine-125 Plaque Radiotherapy for Residual or Recurrent Retinoblastoma.

Abstract Objective To determine the role of iodine-125 plaque radiotherapy (IPR) as a secondary treatment for localized (solitary or multiple) residual (partially regressed) or recurrent (regrowth after ≥6 months stability) retinoblastoma in the era of systemic and/or regional chemotherapy. Design A single-institute retrospective, noncomparative, interventional case series managed between July 2014 and June 2019. Participants Thirteen consecutive eyes of 12 patients with 14 residual or recurrent retinoblastoma tumors treated with IPR. Patients who had to follow up Methods Data collected included pre-IPR treatments, tumor characteristics at IPR, and post-IPR anatomical outcome (local tumor control and globe salvage) and functional outcome (radiation complications). Results Local tumor control was achievable in 12 of 14 tumors. Local recurrences were observed in 2 of 5 tumors that exhibited fish-flesh regression after IPR (p = 0.04). Globe salvage was possible in 11 eyes (12 tumors). Only 2 eyes were legally blind and the remaining 9 eyes had vision >20/125. Radiation-induced complications included radiation retinopathy (4/11), radiation papillopathy (1/11), diffuse vitreous hemorrhage (4/11). Eyes with fish-flesh-regressed tumours tended to show more complications, but were statistically insignificant (p = 0.09, Fisher exact test). There was no association of time to IPR (early 6 months) with occurrence of tumor recurrence or complications (p > 0.05). Conclusion IPR offers satisfactory local tumor control and globe salvage in localized recurrent/residual retinoblastoma. Fish-flesh tumor regression after IPR should be closely monitored for further recurrences.