Long-term Outcomes and Prognostic Factors of Eye-preserving Treatment with Particle Beam Radiotherapy for Orbital Malignancies

Background This retrospective study report the clinical experience of eye-preserving treatment follow by particle beam radiotherapy (IMPT or CIRT) for orbital malignancies. And to evaluate prognostic factors for orbital and lacrimal gland tumors. Methods Sixty-two patients with orbital malignancies were identified in the records of a single center between 2015 and 2021. Sixty-one patients met inclusion criteria. All of the patients received eye-preserving treatment before PBRT. Majority of the patients (91.8%) were treatment with CIRT. Clinical data, treatment modality, local control, metastases and survivals and visual outcomes, as well as associated prognostic indicators were were assessed. Results Sixty-one patients were followed with a median of 40.7 months (44.3 months for surviving patients). The 3- and 5-year DSS and LC rates were 88.1% and 69.9%, and the 3- and 5-year DMC rates were 77.5% and 74.2% for entire orbital malignancies. For lacrimal gland carcinoma, the 5-year DSS, LC, DMC, and PFS rates were 83.3%, 64.8%, 66.8%, and 53.4%. Tumor size, T stage, extraorbital invasion, and bone invasion influenced survivals. No grade 3 or higher acute toxicities were observed. A total of 8 patients experienced grade 3–4 visual impairment. Conclusions Particle radiotherapy following eye-preserving treatment provided a favorable local control and survivals with moderate acute and late toxicities, even in patients with unresectable disease. Particle radiotherapy was a promising strategy for management of orbital tumors.