Proton beam radiotherapy of iris melanoma

doi:10.1016/j.ijrobp.2005.01.050

International Journal of Radiation OncologyBiologyPhysics

Volume 63, Issue 1, 1 September 2005, Pages 109-115

https://doi.org/10.1016/j.ijrobp.2005.01.050 Get rights and content

Purpose: To report on outcomes after proton beam radiotherapy of iris melanoma.

Methods and Materials: Between 1993 and 2004, 88 patients with iris melanoma received proton beam radiotherapy, with 53.1 Gy in 4 fractions.

Results: The patients had a mean age of 52 years and a median follow-up of 2.7 years. The tumors had a median diameter of 4.3 mm, involving more than 2 clock hours of iris in 32% of patients and more than 2 hours of angle in 27%. The ciliary body was involved in 20%. Cataract was present in 13 patients before treatment and subsequently developed in another 18. Cataract had a 4-year rate of 63% and by Cox analysis was related to age (p = 0.05), initial visual loss (p < 0.0001), iris involvement (p < 0.0001), and tumor thickness (p < 0.0001). Glaucoma was present before treatment in 13 patients and developed after treatment in another 3. Three eyes were enucleated, all because of recurrence, which had an actuarial 4-year rate of 3.3% (95% CI 0–8.0%).

Conclusions: Proton beam radiotherapy of iris melanoma is well tolerated, the main problems being radiation-cataract, which was treatable, and preexisting glaucoma, which in several patients was difficult to control.

Introduction

Iris melanomas account for approximately 3–5% of all uveal melanomas (1). Without treatment, they can grow, seed throughout the anterior chamber, invade the drainage angle to cause secondary glaucoma, and spread extraocularly. Approximately 5–10% of patients die of metastatic disease within 10 years of treatment (2, 3).

The standard form of treatment for iris melanoma is iridectomy, with iridocyclectomy being performed if the tumor extends to angle or ciliary body (4). The surgical iris defect tends to cause photophobia, and cyclectomy can cause lens subluxation, hypotony, and phthisis. To prevent local tumor recurrence, iridocyclectomy can be performed with adjunctive plaque radiotherapy or a full-thickness corneo-scleral excision followed by a tectonic graft (5). Primary brachytherapy has been advocated for patients with extensive iris melanoma, and good results have been reported (6, 7).

Proton beam radiotherapy has been used for the treatment of ciliary body and choroidal melanomas for several decades, with excellent rates of local tumor control (8, 9). However, to our knowledge this modality has not previously been advocated for the treatment of iris melanomas. In 1994, it occurred to one of us (B.D.) that in view of the limitations of surgical resection and plaque radiotherapy of iris melanomas there was scope for treating iris melanomas with proton beam radiotherapy.

The aim of the present study was to evaluate the early results of proton beam radiotherapy of iris melanoma, measuring outcomes in terms of visual acuity and ocular complications.

Section snippets

Patients and methods

Patients were included in the study if (1) they were managed at the Liverpool Ocular Oncology Centre and Clatterbridge Centre for Oncology between 1994, when the first patient was treated, and September 15, 2004, when the study was closed; (2) the tumor was diagnosed as a melanoma, either clinically or histologically; (3) the primary treatment consisted of proton beam radiotherapy; and (4) at the time of our initial examination the tumor was considered to originate in iris. Patients were

Results

The sample comprised 88 patients (56% female, 44% male). The age at treatment averaged 52.0 years (range, 21–76 years). The follow-up had a median of 2.7 years, exceeding 1 year in 72 patients, 2 years in 54 patients, and 4 years in 32 patients. The tumor was located in the right eye in 51% patients and the left eye in 49% patients. The visual acuity before treatment was 20/17 (40%), 20/20 (36%), 20/30 (15%), 20/40 (3%), 20/60 (1%), 20/80 (1%), 20/200 (1%), Counting Fingers (1%), and Light

Discussion

This prospective, noncomparative, interventional study found that proton beam radiotherapy of iris melanoma was well tolerated, the main complication being cataract. No patients developed iris neovascularization, despite irradiation of iris and ciliary body. To our knowledge, there have not been any published studies on proton beam radiotherapy of iris melanoma. The main strengths of this study are the large number of cases, the length of follow-up, and the treatment at a single center.

We did

Acknowledgments

The authors wish to thank Mr. Gary Cheetham for database support, Jane Kongerud, Martin Sheen, and Kathy Sztanko for radiotherapy planning and administration, and the National Specialist Commissioning Advisory Group (NSCAG) for funding of our service.

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Clinical investigationEyeProton beam radiotherapy of iris melanoma

Introduction

Section snippets

Patients and methods

Results

Discussion

Acknowledgments

Am J Ophthalmol

Ophthalmology

Am J Ophthalmol

Int J Radiat Oncol Biol Phys

Int J Radiat Oncol Biol Phys

Primary iris melanomaDiagnostic features and outcome of conservative surgical treatment

Br J Ophthalmol

Clinical investigation
Eye
Proton beam radiotherapy of iris melanoma