Development of a Streamlined, Non-invasive Robotic Radiosurgery Method for Treatment of Uveal Melanoma

Abstract

To analyze the feasibility and safety of frameless, image-guided robotic radiosurgery against uveal melanoma, we developed a streamlined procedure that is completed within 3 hours under retrobulbar anesthesia without immobilization. Twenty patients (10 men and 10 women) with medium (3-5-mm prominence) and large (>5-mm prominence) unilateral uveal melanomas were treated with a frameless robotic radiosurgery system. Median age was 61 years (range 32-78 years). All patients underwent a single-session procedure beginning with retrobulbar anaesthesia, followed by computerized tomography (CT) scanning that was used in the generation of a treatment plan, and then the delivery of a radiosurgical tumor dose between 18 and 22 Gy to the 70% isodose line. Three-dimensional treatment planning was aimed at securing the optical lens and the optic disc as much as possible. Follow-up occurred at 3, 6, 12, and 18 months after the radiosurgery with clinical, ultrasound, and CT studies.We were able to treat all patients in the frameless setup within 3 hours. In five patients with lateral and dorsal tumors, the dose to the optic lens could be kept below 2 Gy. The clinical response was evaluated for the first seven patients treated with a follow-up of at least 6 months. No local recurrences occurred with any of the clinically evaluated patients for a mean 13-month follow-up (range 6-22 months). Maximum median apical tumor height according to standardized A-scan ultrasound evaluations decreased from 7.7 to 5.6 mm (p < 0.1). The median reflectivity increased from 41% to 70% (p < 0.01). None of the patients developed a secondary glaucoma during the short-term follow-up period. Frameless, singlesession, image-guided robotic radiosurgery is a feasible, safe and comfortable treatment option for patients with uveal melanoma. Longer follow-up and analysis of a larger patient series is required for definitive clinical recommendations.

Robotic radiosurgery for the treatment of medium and large uveal melanoma

“…Hirasawa et al [29] have identified the anterior segment of the eye and the optic disc as structures of great risk for neovascular glaucoma based on a multivariate analysis, and recommended irradiation techniques that would spare these structures as much as possible when treating uveal melanoma. The high flexibility of the robotic technology used in the current study is capable of achieving this goal [2,3,10]. Although these data cannot be directly correlated to visual outcome, it clearly documents the ability of the robotic system to adjust the dose to the tumor as much as possible by maximally sparing the sensitive structures of the eye from the dose.…”

“…This was the cutoff used for follow-up of visual function. All patients underwent a standardized outpatient procedure, which has been described previously [10] and is composed of the following steps. Patients underwent standard retrobulbar anesthesia with the goal of complete akinesia of the globe within the orbit.…”

“…As the Collaborative Ocular Melanoma Study (COMS) has demonstrated that metastasis and overall survival rates do not differ significantly between patients treated with enucleation and those treated with brachytherapy, eye retention is feasible [1]. Whereas brachytherapy with radioactive eye plaques can only be delivered to patients with uveal melanoma of limited height and transverse diameter, teletherapy approaches such as fractionated proton beam therapy, conventional LINAC radiotherapy, and frame-based radiosurgical techniques can be applied successfully to larger tumor volumes as well as to tumors located close to the posterior pole of the eye [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Each radiotherapy regimen has its advantages but also brings radiation-specific complications.…”

Quality of life in the follow-up of uveal melanoma patients after CyberKnife treatment

“…Current designs and techniques of radiation therapy need to be explored [16]. First studies on CyberKnife radiosurgery as a locoregional treatment for uveal melanoma showed promising results without serious acute adverse events [15,17].…”

Cyberknife®-Chirurgie mit dem Strahlenmesser: eine neue Behandlungsalternative für Patienten mit inoperablen Metastasen

“…Mit der Cyberknife-Therapie sind diese Schwachpunkte eliminiert. So ist eine superselektive Behandlung von Metastasen auch in bewegten Organstrukturen nach radiologisch interventioneller Platzierung eines Goldmarkers (fiducial) in einer einzigen ambulanten Bestrahlungsbehandlung ohne Fixierung des Patienten und mit lediglich minimaler Strahlenbelastung des umgebenden Gewebes möglich [24][25][26].…”