Carbon Ion Versus Photon-based Stereotactic Ablative Radiation Therapy for Patients with Choroidal Melanoma

Abstract

Purpose: To our knowledge, no study has compared the treatment outcomes of carbon ion radiation therapy (CIRT) and photon-based stereotactic ablative radiation therapy (SABR) in patients with choroidal melanoma. This study aimed to evaluate the treatment outcomes of patients with choroidal melanoma treated with CIRT or photon-based SABR. Methods and Materials: This study included 346 patients with localized choroidal melanoma who received CIRT or photon-based SABR between April 2001 and November 2021. Patients in the CIRT group received a median of 70 Gy delivered in a median dosage of 14 Gy per fraction, and patients in the SABR group received a median of 60 Gy delivered in a median dosage of 15 Gy per fraction. Propensity score matching (PSM) was performed to account for differences between the 2 groups. The main outcome was progression-free survival (PFS) in the PSM cohort, and secondary endpoints included overall survival, cumulative incidence of local and distant failures, and enucleation. Results: In all, 282 and 64 patients were included in the CIRT and SABR groups. After PSM, the 5-year PFS was significantly superior in the CIRT group to that in the SABR group (69.0% vs 56.5%, P = .024). The CIRT group also showed significantly reduced risks of local failure (5-year local failure rate 5.6% vs 13.4%, P = .025) and enucleation (5-year enucleation rate 8.5% vs 24.2%, P < .001). Moreover, CIRT was superior in terms of visual acuity preservation: the proportion of patients with visual acuity of >= 20/200 decreased from 64.7% initially to 23.7% at last follow-up in the CIRT group and from 64.1% to 6.3% in the SABR group (P = .005). Conclusions: CIRT was found to be superior to SABR in patients with choroidal melanoma in terms of PFS, local control, and preservation of vision and eye.