Outcomes of plaque radiotherapy for retinoblastoma
Reviewed by Fiona Rowe

The study authors evaluate their experience of plaque radiotherapy for retinoblastoma (RB) in 41 eyes of 41 patients that failed intra-arterial chemotherapy (IAC). This was a retrospective review including 21 females and 20 males. Median age was 18 months and mean age was 24 months (range 1.7 to 57 months). Twenty-two had unilateral and 19 had bilateral disease. Forty-one eyes received a median of three cycles of IAC (range 1-7 cycles) with melphalan (n=40), topotecan (n=26) and / or carboplatin (n=3) at median doses of 15, 3 and 30mg respectively. Treatment was suspended for 10. Main indications included solid tumour recurrence, subretinal seed recurrence and vitreous seed recurrence. Mean plaque diameter was 16mm; median 15mm (range 10-20mm) and mean dose delivery was 3483 centigray (cGy) to the tumour apex at a mean dose rate of 35 cGy/hour. Mean dose to the tumour base was 8991 cGy at a mean dose rate of 90 cGy/hour. Mean dose to the macula was 3270 cGy and to the disc was 1922 cGy. Outcomes included complete tumour control at the target site in 39 eyes at a median follow-up of 20 months. Complete tumour regression was noted in 31/33 eyes with solid recurrence, 6/6 eyes with subretinal seeding and 2/2 eyes with vitreous seeding. No case had metastatic disease or death during follow-up. Globe salvage was possible for 36 patients. Complications for 22 eyes included radiation retinopathy, vitreous haemorrhage, cataract, iris neovascularisation and cystoid macular oedema. These authors believe this to be the first study to address recurrences associated with an ischaemic calcific remnant of RB. These results indicate a two-year recurrence-free survival estimate of 93% for in-target area. Close monitoring is key. They propose Iodine-125 plaque radiotherapy as an effective salvage treatment.

Iodine-125 plaque radiotherapy for retinoblastoma recurrence following intra-arterial chemotherapy.
Ruben M, Eiger-Moscovich M, Yaghy A et al.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2022;59(3):164-71.