CyberKnife Stereotactic Radiosurgery for Uveal Melanoma: First Case Series in Central America

Abstract

Introduction: Uveal melanoma is the most common primary intraocular malignancy in adults, affecting primarily the choroid of the eye. Plaque brachytherapy is the most common procedure for the treatment of small choroidal melanoma, especially in posteriorly located tumors. However, modern radiotherapy techniques, such as CyberKnife or Gamma knife stereotactic radiosurgery (SRS) and proton beam radiotherapy, have shown better results in tumor control and eye retention. Recent studies have indicated that SRS is a promising non-invasive, single-session treatment option, with most studies reporting the best outcomes when using ≥21-22 Gy. However, there is no consistent protocol for managing this pathology using CyberKnife, not only in terms of dose but also fractions.

Case presentations: Here, we report the first case series of patients (n = 4, age range 38-64 years, median age 52.5 years) with choroidal UM in Central America who were treated with CyberKnife SRS (22 Gy in one session). During the follow-up (range 25-29 months, median 27.5 months), a 100% control rate with no systemic metastatic disease has been achieved. We found a statistically significant reduction in the largest basal diameter at 24 months for all tumors. However, visual acuity has progressively decreased in most patients. Notably, two of our patients developed radiation maculopathy, and the other two developed radiation retinopathy after SRS.

Conclusions: Our findings suggest that future studies should evaluate the use of different prophylactic therapies to prevent the development of side effects. The clinical management of toxicities presented in our report can serve as a reference in the clinical practice of other centers. Our report supports the growing body of evidence showing that CyberKnife radiosurgery is a safe and effective therapeutic option for the treatment of UM.

Keywords: Choroidal melanoma; CyberKnife; Ocular oncology; Stereotactic radiosurgery; Uveal melanoma.

Fig. 1.

Comparison of longitudinal B-scan ultrasounds at diagnosis (Dx) and 24 months (24M) after SRS (left panel). Comparison of the largest basal diameter (longitudinal B-scan ultrasound) at diagnosis (Dx) and 24 months (24M) after SRS (one tail, paired t-test, p value = 0.034) (right panel).

Fig. 2.

Magnetic resonance images (T2 sequence) in axial, sagittal, and coronal sections and 3D reconstruction of the treatment plans for patient 1 (a), patient 2 (b), patient 3 (c), and patient 4 (d). Dose conformation is represented by the colored lines, ranging from 20% to 100% of the dose (thick orange line is the prescription isodose).