Plaque Radiotherapy for Ocular Melanoma

Abstract

Plaque radiotherapy is an effective treatment modality for medium-sized ocular tumors such as uveal melanoma. The authors review the available literature and concisely summarize the current state of the art of ophthalmic plaque brachytherapy. The choice of radioisotope, which includes Ruthenium-106 and Iodine-125, depends on the intended treatment duration, tumor characteristics, and side effect profiles. Ophthalmic plaques may be customized to allow for the delivery of a precise radiation dose by adjusting seed placement and plaque shape to minimize collateral tissue radiation. High dose rate (HDR) brachytherapy, using beta (e.g., Yttrium-90) and photon-emitting sources (e.g., Ytterbium-169, Selenium-75), allows for rapid radiation dose delivery, which typically lasts minutes, compared to multiple days with low-dose plaque brachytherapy. The efficacy of Ruthenium-106 brachytherapy for uveal melanoma varies widely, with reported local control rates between 59.0% and 98.0%. Factors influencing outcomes include tumor size, thickness, anatomical location, and radiation dose at the tumor apex, with larger and thicker tumors potentially exhibiting poorer response and a higher rate of complications. Plaque brachytherapy is effective for selected tumors, particularly uveal melanoma, providing comparable survival rates to enucleation for medium-sized tumors. The complications of plaque brachytherapy are well described, and many of these are treatable.

Keywords: choroid; ciliary body; melanoma; uvea.

Figure 1

Plaque insertion surgery. (A) Tagging the lateral rectus muscle; (B) disinserting the lateral rectus muscle; (C) passing a traction suture through the stump of the insertion of lateral rectus muscle; (D) passing a scleral suture at the intended location of the anterior eyelet of plaque; (E) placement of the gold plaque with I-125 seeds; (F) anchoring the plaque to the sclera; (G) reattaching the detached lateral rectus; (H) conjunctival closure.