Novel Eye Plaque Designs for Brachytherapy of Iris and Ciliary Body Melanoma and the First Clinical Application

Abstract

Background: While traditional eye plaque brachytherapy can be used for the treatment of iris melanoma, it faces challenges of poor patient tolerability due to cornea-plaque touch caused by radius of curvature mismatch and potential dosimetric inaccuracy from incomplete coverage. We present novel plaque designs and the first clinical application of the plaques for iris melanoma. Methods: Two dome-shaped plaques (EP2132 and EP1930) were designed to vault above the cornea to treat tumors of the iris and ciliary body. Image-based treatment planning of the first 2 clinical cases using the EP2132 plaque covered the tumor base plus a 2 mm margin and the involved ciliary body with at least 75 Gy to the tumor apex. Results: The tumors decreased in size following treatment. The patients tolerated the treatment well. There was no adverse event associated with the traditional iris plaques, such as decreased vision, pain, corneal edema, glaucoma, or cataract. Conclusion: The novel dome-shaped plaques for the treatment of iris melanoma provide effective dose distribution, improved surgical maneuverability, and increased tolerability for the patient. This plaque model can be used to treat iris melanoma of various sizes, configurations, and locations, including the ciliary body. The need for a customized plaque platform for each patient is minimized.

Annulus-shaped I-125 plaque brachytherapy for conjunctival melanoma

“…Novel dome-shaped I-125 Eye Physics plaques were recently used for iris and ciliary body tumors, with unique radio seed orientation and geometric design with central holes to avoid the unnecessary contact and radiation to the cornea. 24 The novel annular Eye Physics plaque construct described here represents a further innovation on this design. Whereas the prior EP dome plaques created air gaps conducive to dosimetric error, the EP donut here can be sutured flush to the globe.…”

Clinical outcomes of Modified Collaborative Ocular Melanoma Study IRIS plaques for treatment of iris, iridociliary, and ciliary body melanoma

“…Shields et al in a study of 144 patients utilizing round, notched, boomerang, doughnut, and custom-designed plaques, noted that recurrence risk increased with lower percentage of plaque coverage of the cornea (hazard ratio: 1.52, 95% confidence interval: 1.13-2.04, p = 0.006), with mean corneal plaque coverage of 30% for patients with recurrence and 63.7% for those with no recurrence. Other reported cases of specialized iris plaques include novel dome-shaped plaques with a smaller curvature radius to avoid plaque-corneal contact in two cases by Liu et al [22], and modified Silastic inserts to improve plaque-cornea conformance in one case by Scanderbeg et al [23].…”

Uveal melanoma: laboratory advances and new frontiers in patient care

“…Patient-specific customization of radiotherapy may also be an avenue to mitigate vision-limiting radiation side effects. In plaque radiotherapy for the management of iris melanoma, custom-shaped plaques based on tumor extent have been used to decrease radiation to unaffected structures [33 ▪ ,34,35,36 ▪ ]. In a study of 22 patients with iris melanoma, Xu et al reported the use of segmental arcs of the dome-shaped traditional Collaborative Ocular Melanoma Study plaque to reduce radiation exposure outside the intended treatment area [33 ▪ ].…”

“…Radiation side effects that could be adequately managed in follow-up included cataract (77%) and dry eye (23%), whereas vision-threatening complications such as neovascularization of the iris (5%) and neovascular glaucoma (5%) rarely occurred [33 ▪ ]. The body of literature regarding customized plaque radiotherapy and individualized planning for charged particle therapies continues to grow [34,35,36 ▪ ,37,38].…”