Outcomes of Stereotactic Body Radiation Therapy for Large Uveal Melanoma: A Retrospective Analysis of Asian Population

Purpose: To investigate the clinical outcomes of stereotactic body radiation therapy (SBRT) in patients with large uveal melanoma (UM).

Materials and methods: We conducted a retrospective review of 64 consecutive patients with UM treated with Cyberknife at Yonsei Cancer Center from September 2015 to October 2021. The median radiation dose was 60 Gy (range 48-64 Gy) administered in four fractions every alternate day. The local failure-free rate (LFFR), distant metastasis-free rate (DMFR), progression-free survival (PFS), and overall survival (OS) were assessed using the Kaplan-Meier method and log-rank test. Cox regression analysis was performed to analyze the predictive factors affecting survival outcomes and the factors associated with vision loss.

Results: The median tumor diameter and height were 11.5 mm and 8.4 mm, respectively. After a median follow-up of 32.1 months (range 4.9-89.9), the 3-year LFFR, DMFR, PFS, and OS were 89.5%, 70.5%, 65.5%, and 89.4%, respectively. Enucleation was performed in 13 (20.3%) patients, with three cases attributed to disease progression. A larger tumor diameter was associated with significantly worse DMFR (HR=1.35, p=0.015) and OS (HR=1.49, p=0.026) in the multivariate analysis. Regarding visual prognosis, 41 (64.1%) patients had baseline visual acuity ≥20/200, but only 4 (6.3%) patients maintained visual acuity ≥20/200 by the final follow-up. Initial visual acuity ≥20/40 (HR 0.45, p=0.030) was the single favorable significant factor predicting visual retention ≥20/200 in multivariate analysis.

Conclusion: SBRT using CyberKnife demonstrated a comparable local control rate to that observed in historical studies for patients with large UM. Distant metastasis and treatment-related ocular toxicity remain the limitations of this treatment.