Abstract
Purpose:
Proton radiotherapy allows highly focal tumor targeting with sub-millimeter precision while minimizing exposure of surrounding tissues. Of note, tissues distal to the target volume are completely spared. We present one of the first reports of proton therapy as a primary or salvage treatment modality in the management of intraocular retinoblastoma.
Methods:
This was a consecutive, retrospective, interventional case series of patients from 1990 to 2013.
Results:
Forty-seven subjects were identified, and 11 were excluded, resulting in 46 eyes from 36 patients for analyses. Median age at diagnosis was 248.5 days (range 6 days to 2.5 years), and 33 (92%) had bilateral disease. Eyes were treated using 40-46.8 Gy(RBE) (Gray, Radiobiological Equivalent), divided into 20-26 fractions. Median follow-up after proton therapy was 6.8 years (range 1.1-22.1 years). Proton therapy was used as the primary treatment modality in 24 eyes. Tumor control was achieved in 19 (79%) eyes; 9 of 10 (90%) Group B, 3 of 4 (75%) Group C, 6 of 9 (67%) Group D, 1 of 1 (100%) Group E; 3 of 3 (100%) Reese-Ellsworth Group I, 7 of 7 (100%) Group II, 3 of 4 (75%) Group III, 1 of 4 (25%) Group IV, and 5 of 6 (83%) Group V. Twenty-two received proton therapy as salvage therapy; 18 after failed chemoreduction, 3 after failed focal ablation, and 1 after failed intra-arterial chemotherapy. Tumor control was achieved in 18 (82%) of eyes; 8 of 9 (89%) Group B, 5 of 5 (100%) Group C, 4 of 7 (57%) Group D, and 1 of 1 (100%) Group E; 3 of 3 (100%) Reese-Ellsworth Group I, 3 of 3 (100%) Group II, 4 of 4 (100%) Group III, 1 of 1 (100%) Group IV, and 7 of 11 (64%) Group V. Of eyes with tumor control, 7 (26%) underwent cataract extraction, 4 (15%) developed radiation retinopathy, and 1 (4%) developed radiation optic neuropathy. Median final visual acuity was 20/70 (range 20/16-NLP), and 18 (67%) had final visual acuity > 20/200. There were no cases of in-field secondary malignancies, and all patients survived.
Conclusions:
Proton radiotherapy achieved excellent tumor control both as a primary or salvage treatment modality, without inducing any cases of in-field secondary malignancies.
Keywords: 703 retinoblastoma •
671 radiation therapy •
624 oncology