Choroidal melanoma: does endoresection prevent neovascular glaucoma in patient treated with proton beam irradiation?

PURPOSE: To evaluate the efficacy of endoresection after proton beam radiotherapy to prevent neovascular glaucoma (NVG) in patients treated for choroidal melanoma. METHODS: From a series of 4,867 patients treated for choroidal melanoma were prospectively recorded in the database (Macro Infermed 3.075). One hundred and seventy-one patients presenting a tumor diameter >10 mm and thickness >5 mm treated with proton beam (PB) radiotherapy were selected. One group of 63 patients was treated with PB therapy followed by endoresection (PE) of the scar. This group was compared with 2 historical matched controlled groups: 57 patients treated with PB therapy alone (P) and 51 patients treated with PB therapy followed by transpupillary thermotherapy of the scar (PTTT). Main outcome measures are as follows: age, gender, tumor diameter, tumor thickness, pre- and posttreatment visual acuity, NVG rate, secondary enucleation rate, and 5-year survival. Statistical analysis was performed using R version 2.5.1 software. RESULTS: Correlations between the 3 groups were P = 0.29 for age, P = 4.7×10 for tumor diameter, and P = 6.44×10 for tumor thickness. Comparison between the 3 groups showed that 2-year survival without secondary enucleation was 96.2% for PE, 88.8% for P, and 98% for PTTT (P = 0.203) (95% confidence interval). Two-year survival without NVG (95% confidence interval) was 92.7% (85.1-1.00) for PE, 54.6% for P, and 62.1% for PTTT (P = 0.0001). The difference between the endoresection (PE) group and the PB radiotherapy (P) and PB radiotherapy + TTT (PTTT) groups in terms of reduction of the NVG rate was statistically significant. Relative risk of developing NVG was calculated with the P group as reference, relative risk = 1. The relative risk of the PTTT group was 0.79 (20% reduction of the risk), and the relative risk of the PE group was 0.18 (82% reduction of the risk of developing NVG). CONCLUSION: This study shows that endoresection of the necrotic scar after PB radiotherapy reduces the risk of NVG and secondary enucleation for selected choroidal melanoma patients.