A Five-Year Study of Slotted Eye Plaque Radiation Therapy for Choroidal Melanoma: Near, Touching, or Surrounding the Optic Nerve

Abstract

To evaluate slotted eye plaque radiation therapy for choroidal melanomas near the optic disc. A clinical case series. Twenty-four consecutive patients with uveal melanomas that were near, touching, or surrounding the optic disc. Slotted eye plaque radiation therapy. Recorded characteristics were related to patient, clinical, and ophthalmic imaging. Data included change in visual acuity, tumor size, recurrence, eye retention, and metastasis. From 2005 to 2010, 24 consecutive patients were treated with custom-sized plaques with 8-mm-wide, variable-depth slots. Radiation doses ranged from 69.3 to 163.8 Gy (mean, 85.0 Gy) based on delivering a minimum tumor dose of 85 Gy. All treatments were continuously delivered over 5 to 7 days. Mean patient age at presentation was 57 years. Tumors were within 1.5 mm of the optic nerve (n = 3, 13%), juxtapapillary (n = 6, 25%), touching ≥180 degrees (n = 7, 29%), or circumpapillary (n = 8, 33%). Ultrasound revealed dome-shaped tumors in 79% of patients, collar-button tumors in 17% of patients, irregular tumor in 1 patient (4%), and intraneural invasion in 2 patients. Mean initial largest basal dimension was 11.0 mm (standard deviation [SD] ± 3.5 mm; median, 11.4 mm; range, 5.9-16.4 mm). Mean initial tumor thickness was 3.5 mm (SD ± 1.7 mm; median, 3.0 mm; range, 1.4-6.9 mm). Initial visual acuities were a median 20/25 (range, 20/20 to hand motions) and decreased to a median 20/40 (range, 20/20 to no light perception). At a mean follow-up of 23 months, 12 patients required periodic intravitreal bevacizumab to suppress radiation optic neuropathy (RON) or maculopathy. To date, there has been a 100% local control rate. No patients have required secondary enucleation for recurrence or neovascular glaucoma. No patients have developed metastasis. Slotted plaque radiation therapy allows peripapillary, juxtapapilary, and circumpapillary choroidal melanomas (and a safety margin) to be included in the radiation targeted zone. Normalization of the plaque position beneath the tumor appears to increase RON and improve local control.