ИСТИНА

Background: In some cases of chemoresistant or recurrent intraocular retinoblastoma (Rb) external beam radiotherapy (RT) is the only way to save the eye. Due to severe complications conventional RT currently has very limited use. To the best of our knowledge there is no information concerning Gamma-knife radiosurgery (GKRS) in the management of Rb. Purpose: To present the three-year experience of single fraction GKRS of Rb as an alternative to enucleation. Methods: Since June 2015 fifteen eyes of 14 patients aged from 12 to 114 months (mean 35) with Rb Group B (n=4), Group C (n=1) and Group D (n=10) were treated with GKRS. All patients previously were treated with all kinds of chemotherapy including systemic, intra-arterial, and intravitreal, different kinds of focal ophthalmological treatment. Due to different reasons there were no capabilities to preserve the eye using conventional approaches. Three types of dosimetric plans were used and will be presented – single PTV for the whole vitreous cavity (3 eyes), PTV for single retinal or vitreous tumor (8 eyes), and double PTVs for double retinal tumors or retinal and vitreous lesions (4 eyes). In cases of massive vitreous Rb (4 patients) irradiation dose of 20-22 Gy at 50% isodose was prescribed along the inner MRI/CT contour of the eye globe and the lens. The retinal tumors were treated with 22-24 Gy at 50% isodose. Doses for critical structures of the eye and orbit have been also taken into consideration, and will be presented. Results: Fourteen eyes were preserved. Complete tumor regression was achieved in 11 eyes. In 3 eyes more than 50% regression was seen. One eye was enucleated because of suspicion of tumor progression. Complications were analysed according to time after chemotherapy. Vitreous hemorrhage occurred in 4 patients and was successfully managed conservatively or surgically with intraocular Melphalan irrigation. In 5 eyes mild to moderate optic neuropathy and/or retinopathy developed. In 3 eyes retinal detachment occurred. One eye developed eccentric opacities of posterior lens capsule. No signs of iridocyclitis, keratopathy, and damage of orbital tissues, bones, or brain were seen. Follow-up was from 4 to 41 months (mean 12.5). Conclusions: The three-year experience of GKRS for Rb showed that it may be a reasonable treatment approach as an alternative to enucleation in selective cases.