A five-year study of slotted eye plaque radiation therapy for choroidal melanoma: near, touching, or surrounding the optic nerve

Abstract

Objective: To evaluate slotted eye plaque radiation therapy for choroidal melanomas near the optic disc.

Design: A clinical case series.

Participants: Twenty-four consecutive patients with uveal melanomas that were near, touching, or surrounding the optic disc.

Intervention: Slotted eye plaque radiation therapy.

Main outcome measures: Recorded characteristics were related to patient, clinical, and ophthalmic imaging. Data included change in visual acuity, tumor size, recurrence, eye retention, and metastasis.

Results: 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.

Conclusions: 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.