Outcomes of Volumetric-Modulated Arc Therapy for Refractory, Corticosteroid-Resistant Orbital Inflammatory Diseases

This study aimed to evaluate the efficacy and safety of volumetric-modulated arc therapy (VMAT) in treating corticosteroid-resistant orbital inflammatory diseases, with a focus on radiation therapy (RT) plan design, clinical outcomes, and the incidence of treatment-related side effects.

A retrospective analysis was conducted on 57 patients with refractory, corticosteroid-resistant orbital inflammatory diseases treated with orbital VMAT from November 2019 to July 2022. The primary endpoint was the reduction or cessation of corticosteroid use following RT, with secondary endpoints, including improvements in ocular clinical symptoms (diplopia, proptosis, visual acuity, and extraocular movement) and long-term side effects.

The median target dose was 20 Gy, with an average lens irradiation dose of 5.4 Gy. Initially, all 57 patients received corticosteroids. After a median follow-up of 27.5 months, 89.5% (51 of 57) of patients responded positively to RT; in particular, 56.1% (32 of 57) completely tapered off corticosteroids, whereas 33.3% (19 of 57) reduced their dosage. Symptomatic improvements were observed in diplopia (67.3%), proptosis (64.7%), visual acuity (56.1%), and extraocular movements (65.9%). Regarding the long-term side effects of RT, incidences of dry eye syndrome and lens opacities were reported at 3.5% and 1.8%, respectively.

Orbital VMAT is an effective treatment for refractory, corticosteroid-resistant orbital inflammatory diseases, reducing corticosteroid use and improving ocular symptoms with minimal side effects. Further prospective clinical trials are warranted to validate more appropriate VMAT doses and planning models, enhancing treatment outcomes without increasing RT side effects.