Treatment of Uveal Melanoma Using a Novel Radiosurgical Platform: A Case Report

We report on a patient with uveal melanoma treated with radiosurgery using the ZAP-X^® system (Zap Surgical Systems Inc., San Carlos, USA), a novel stereotactic radiosurgery delivery system dedicated to the treatment of intracranial lesions. A 78-year-old female patient presented with a collar-button uveal melanoma measuring 9.90 mm in the largest basal diameter and 12.97 mm in ultrasonographic thickness with associated neurosensory detachment. The gross tumor volume (GTV) in the right eye was 1.47 cm³ and was defined geometrically and stereotactically in three dimensions using imaging data. The planning target volume (PTV) was created by adding a 2-mm isotropic margin around the GTV to account for setup and patient uncertainties. The maximum dose of 33.3 Gy was used in the center, and a prescription dose of 18 Gy was applied to the 54% isodose around the PTV. Akinesia of the ocular globe was achieved by mechanical vacuum fixation, and pupil center deviation was continuously assessed during treatment via an infrared camera to stop dose delivery instantly in case of abnormal bulbus movement. Treatment was delivered in a single session. Follow-up after 6 and 12 months showed a reduction in the volume of the melanoma. No major complications were recorded. This report details the case of one of the first patients to be successfully treated for uveal melanoma using the ZAP-X^® radiosurgery platform. The results demonstrate that this approach can be safely applied and shows potential indicating that it is an important alternative to existing treatment modalities.