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

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.

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.

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).

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.