Adjuvant Brachytherapy Using Iodine-125 Plaques for Conjunctival Melanoma with Scleral Invasion

To report a series of patients with unresectable conjunctival melanoma treated with surgical excision followed by adjuvant iodine-125 plaque brachytherapy.

A retrospective review of a consecutive series of patients at one institution who were found to have scleral-invasive conjunctival melanoma and who were treated with adjuvant plaque brachytherapy. Pre-operative, radiation, and post-operative data were collected for each patient. Patients were evaluated for intraocular pressure, visual acuity (VA), radiation complications, local recurrence, and presence of metastatic disease.

A total of 9 patients met inclusion criteria. After surgical excision, all 9 patients were treated with iodine-125 plaque brachytherapy with a dose of 85 Gy to a depth of 3 mm from the plaque face for a prescribed dwell time of 2-3 days. Patients were followed for a median of 45 months (range: 3-66). There have been no local recurrences to this point. Following surgery, 4 of the 9 patients maintained a VA of 20/50 or better. Overall mean visual acuity declined from Snellen 20/59 preoperatively to 20/209 postoperatively. Limbal stem cell deficiency occurred in 3 patients (33%) but may be explained by additional treatments provided in each of these patients (mitomycin C eyedrops in two and proton beam radiation in one). One patient with a second, high-risk forniceal conjunctival melanoma developed metastatic disease.

Plaque brachytherapy with iodine-125, delivering a dose of 85 Gy to a depth of 3 mm over a short period of time (3 days) provides safe and promising results for vision and tumor control in patients with scleral-invasive conjunctival melanoma.