HyperArc radiotherapy for unresectable benign orbital tumours-cohort study and dosimetric comparison study

Area of Science:

• Radiation Oncology
• Neurosurgery
• Ophthalmology

Background:

• Benign orbital tumors pose treatment challenges, especially when surgery is not feasible.
• Radiotherapy is an option for these tumors, but optimizing dosimetry to protect surrounding structures is crucial.

Purpose of the Study:

• To evaluate the clinical application, dosimetric benefits, efficacy, and toxicity of HyperArc (HA) for benign orbital tumors.
• To compare the dosimetry of HA with volumetric modulated arc therapy (VMAT).

Main Methods:

• Retrospective cohort study of eight patients with benign orbital tumors treated with HA.
• Dosimetric comparison between HA and VMAT for planning target volume coverage and organs at risk (OARs).
• Clinical and radiological follow-up for response and toxicity assessment.

Main Results:

• All eight patients showed tumor regression (mean volume reduction from 4916 mm³ to 3239 mm³).
• Three patients experienced improved vision, three maintained pre-treatment vision, and two had reduced vision.
• HA demonstrated significantly improved dosimetry for the contralateral lens, lacrimal gland, optic nerve, nasal cavity, and ipsilateral temporal lobe compared to VMAT.

Conclusions:

• HyperArc is an effective and well-tolerated radiotherapy modality for benign orbital tumors.
• This study is the first to report the clinical use of HA for orbital tumors.
• HA offers superior OAR dosimetry compared to VMAT for this patient group.