Complications after radiotherapy in patients with Graves' orbitopathy: A nationwide cohort study

To analyse the incidence of complications following radiotherapy (RT) in patients with Graves' orbitopathy (GO), particularly focusing on the incidence of radiation retinopathy and associated risk factors.

Data on diagnosed GO patients who received RT between 2008 and 2018 were obtained from the National Health Insurance Service database. The diagnosis of GO and the administration of RT were assessed utilising the International Classification of Diseases codes. The incidence of RT-related complications was analysed. Logistic regression was used to identify risk factors for radiation retinopathy.

Among the 1108 patients who received RT for GO between 2008 and 2018, 67 patients (6.0%) were newly diagnosed with cataracts, and 42 patients (3.8%) underwent surgery. Ocular surface disease, dry eye syndrome, eyelid inflammation, and head and neck cancer occurred in 14 patients (1.3%), 37 patients (3.3%), 8 patients (0.7%), and 2 patients (0.2%), respectively, and no cases of leukaemia or lymphoma were observed. Radiation retinopathy developed in 63 patients (5.7%). In comparison to those without radiation retinopathy, patients with radiation retinopathy had a short interval from GO diagnosis to RT (odds ratio (OR) = 0.95, 95% CI = 0.92-0.98, p = 0.003) and high fasting blood sugar levels (OR = 1.01, 95% CI = 1.00-1.03, p = 0.014).

In patients with GO, cataract, radiation retinopathy, dry eye syndrome, ocular surface disease, and head and neck cancers are potential complications of orbital RT. Risk factor identification and long-term monitoring are crucial for minimising treatment-related complications and improving patient outcomes.