Localized whole eye radiotherapy for retinoblastoma using a (125)I applicator, "claws".

Abstract

To treat children with retinoblastoma, who require whole eye radiotherapy, with a specially designed (125)I applicator that irradiates the eye while sparing the surrounding tissues. Under general anesthesia, a pericorneal ring is attached to the 4 extraocular muscles, and 4 appendages, each loaded with (125)I seeds, are inserted beneath the conjunctiva in-between each pair of muscles and attached anteriorly to the ring. Twenty-nine eyes were treated. Eighteen received a median dose of 28 Gy during 91 hours and 11 received 40 Gy during 122 hours, when the relative biologic effectiveness was taken as 1 instead of 1.5. Six had received prior chemotherapy. Twenty-four eyes were followed up for 2-157 months (median 29). Although 22 eyes responded, local control was achieved in 13 patients, 3 of whom required additional treatment for new tumors; a further 3 required additional treatment for tumor recurrence as well as new tumors. One of these eyes was enucleated for neovascular glaucoma. All 6 Group I-III eyes and 6 of 18 Group V eyes were retained for 2-157 months (median 39), with good vision in 10 eyes. Three developed cataracts 7, 8, and 12 years later, 1 of which has been removed. This is a new way of irradiating the whole eye with a minimal dose to the surrounding tissues. The treatment time is only 5 days. It is effective in Groups I-III, but only 33% of Group V eyes retained vision. No late cosmetic defects occurred.