Proton radiation therapy for medium and large choroidal melanoma: Preservation of the eye and its functionality

Purpose: Evaluation of efficacy and safety of proton radiation therapy (PRT) for medium- and large-size choroidal melanoma with focus on preservation of the eye and its function. Methods: Retrospective review of 78 patients with 60 medium and 18 large-size choroidal melanomas at a median follow-up of 34 months. Results: The 5-year data for local control, metastases-free survival, and disease-specific survival were estimated to be 90.5 ± 3.7%, 76.2 ± 6.7%, and 75.6 ± 7.6%, respectively. Eye preservation was achieved in 75.3% of patients, with useful (better than 20/200) visual acuity (VA) in 49.1% of surviving patients. Both local failure and complications led to enucleation. Prognosticators were tumor close to the optic disc (p = 0.003), large tumors involving the ciliary body (p = 0.041), and local failure (p < 0.001). Prognostic factors for VA following PRT were initial VA (p = 0.001), doses to optic disc (p = 0.001) and fovea (p = 0.022) higher than 35 CGE (Cobalt Gray equivalent), tumor close to the optic disc (p = 0.034), and retinal detachment (p < 0.001). Tumor basis diameter was significantly related to metastases free survival (p = 0.02), overall survival (p = 0.033), and disease specific survival (p = 0.017), but did not impair local tumor control, rate of enucleation, and VA. Conclusion: The present data suggest that PRT is an effective and safe treatment for medium and large size choroidal melanoma. PRT can preserve the eye and its function in a reasonable percentage of patients. Further evaluation in controlled clinical trials comparing PRT to plaque radiotherapy and enucleation is required.