Efficacy of orbital radiotherapy in moderate-to-severe active graves’ orbitopathy including long-lasting disease: a retrospective analysis

Background We aimed to explore the efficacy of orbital radiotherapy (RT) in patients with moderate-to-severe active Graves’ orbitopathy (GO), including long-lasting disease, and to determine the predictive factors associated with treatment response. Methods This was a retrospective study of 62 moderate-to-severe active GO patients treated with RT. Demographic data and ophthalmic findings prior to RT and at 3 and 6 months afterward were analyzed. Computed tomography was performed before and after RT to compare orbital volume change. We used logistic regression to determine the predictive factors for treatment response. Subjects were divided into early- and late-active phase groups based on GO duration of 24 months and treatment outcomes were compared with each other to observe the effects of RT timing on treatment response. Results Forty (64.5%) and forty-six (74.1%) patients experienced improvements in GO at 3 and 6 months after radiotherapy, respectively. Ocular parameters such as clinical activity score (CAS), proptosis, extraocular muscle (EOM) limitation, and compressive optic neuropathy (CON) were improved by RT. Volumes of EOM significantly decreased after RT. The enlargement of EOMs and EOM limitation were predictive factors for a good response to RT. At 6 months after RT, 22 (68.8%) patients of late-active phase group exhibited improvement in GO, which is comparable to the number of 24 (80.0%) patients of early-active phase group. In the late-active phase group, CAS, diplopia, and visual acuity were improved significantly, but there was no change in EOM limitation. Conclusions In moderate-to-severe active GO patients, orbital RT may help improve high CAS, proptosis, EOM limitation, and CON. The orbital RT in long-lasting active GO patients may be considered as treatments for the relief of symptoms including high CAS and poor visual acuity.