Clinical Investigation
Stereotactic Fractionated Radiotherapy in the Treatment of Juxtapapillary Choroidal Melanoma: The McGill University Experience

Presented at the 24th Annual Scientific Meeting of the Canadian Association of Radiation Oncology, Vancouver, British Columbia, Sep 22-25, 2010.
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Purpose

To report our experience with linear accelerator-based stereotactic fractionated radiotherapy in the treatment of juxtapapillary choroidal melanoma.

Methods and Materials

We performed a retrospective review of 50 consecutive patients diagnosed with juxtapapillary choroidal melanoma and treated with linear accelerator-based stereotactic fractionated radiotherapy between April 2003 and December 2009. Patients with small to medium sized lesions (Collaborative Ocular Melanoma Study classification) located within 2 mm of the optic disc were included. The prescribed radiation dose was 60 Gy in 10 fractions. The primary endpoints included local control, enucleation-free survival, and complication rates.

Results

The median follow-up was 29 months (range, 1–77 months). There were 31 males and 29 females, with a median age of 69 years (range, 30–92 years). Eighty-four percent of the patients had medium sized lesions, and 16% of patients had small sized lesions. There were four cases of local progression (8%) and three enucleations (6%). Actuarial local control rates at 2 and 5 years were 93% and 86%, respectively. Actuarial enucleation-free survival rates at 2 and 5 years were 94% and 84%, respectively. Actuarial complication rates at 2 and 5 years were 33% and 88%, respectively, for radiation-induced retinopathy; 9.3% and 46.9%, respectively, for dry eye; 12% and 53%, respectively, for cataract; 30% and 90%, respectively, for visual loss [Snellen acuity (decimal equivalent), <0.1]; 11% and 54%, respectively, for optic neuropathy; and 18% and 38%, respectively, for neovascular glaucoma.

Conclusions

Linear accelerator-based stereotactic fractionated radiotherapy using 60 Gy in 10 fractions is safe and has an acceptable toxicity profile. It has been shown to be an effective noninvasive treatment for juxtapapillary choroidal melanomas.

Introduction

Choroidal melanomas arise from melanocytes in the choroid and account for 85% to 90% of all uveal melanomas. Although rare, with an annual incidence of 6 to 7 cases per 1 million people, the disease is nevertheless the most common primary intraocular malignancy in the adult population 1, 2.

Standard treatment previously consisted of complete removal of the tumor by enucleation. However, studies have failed to demonstrate any advantage of enucleation over eye-conserving therapy in reducing metastasis or in improving overall survival 3, 4. The management of choroidal melanomas is aimed at tumor control with organ preservation, prevention of metastasis, and, ultimately, increased overall survival. The choice of the treatment modality depends on tumor size and intraocular location, and various alternatives exist, including photocoagulation, transpupillary thermotherapy, photodynamic therapy, endoresection, and radiotherapy (RT) (5). Basically, enucleation has been reserved for larger tumors, cases in which there is no possibility of vision preservation, and symptomatic lesions or as a salvage approach.

RT in the form of brachytherapy or external beam RT (EBRT) is the standard eye-conserving treatment for choroidal melanomas. Although this disease is historically regarded as radioresistant, studies have shown that RT is effective in achieving local tumor control and improving overall survival 3, 6. Brachytherapy with iodine-125, ruthenium-106, or other isotopes is usually not recommended for juxtapapillary tumors; however, it is used effectively for lesions located away from the optic disc 7, 8. For medium to large sized lesions and tumors located near the optic disc and fovea, EBRT is the recommended treatment modality, allowing more adequate dose coverage of the tumor. Although results with EBRT using charged particles (protons and helium ions) have been reported since the 1970s 9, 10, the use of photon-based stereotactic RT (SRT) is more recent and less frequently reported in the literature. Nevertheless, SRT with Gamma Knife and linear accelerators (LINAC) has presented results that are attractive and comparable to those of proton therapy 11, 12, 13.

Since 2003, the Division of Radiation Oncology at the McGill University Health Centre has adopted the use of LINAC-based fractionated SRT as a treatment option for patients with choroidal melanomas, and results of this experience are presented in this article.

Section snippets

Patients and data collection

From April 2003 to December 2009, 50 consecutive patients with juxtapapillary choroidal melanoma treated with SRT were identified from medical records of Montreal General Hospital (McGill University Health Centre) and Notre Dame Hospital (Centre Hospitalier de l’Université de Montréal). Patients included in the study had lesions that were small or medium sized according to Collaborative Ocular Melanoma Study (COMS) classification (14). All lesions were localized within 2 mm of the optic

Results

Demographics and tumor characteristics are summarized in Table 1. The median GTV and PTV volumes were 560 mm3 (range, 120–1,530 mm3) and 2,100 mm3 (900–4,100 cm3), respectively. The median time elapsed between the last pretreatment ultrasonography and RT start was 1.8 months (range, 0.7–7.4 months).

At 6 months posttreatment, there was a significant decrease in tumor dimensions, as shown in Figure 1. At the last individual follow-up, median tumor height, length, width, and volume were 3 mm

Discussion

Choroidal melanomas of larger dimensions and lesions located close to the optic disc often present technical difficulties for radioactive plaque insertion and adequate dose coverage. Therefore, despite the overall good results obtained with this modality over the years 17, 18, 19, optimal outcomes might be compromised in these specific situations. Lately, there has been a rapid development of novel radiation techniques that have created successful alternatives to plaque RT. These treatments

Conclusions

Our study using LINAC-based stereotactic fractionated RT with 60 Gy in 10 fractions has shown that this technique at McGill University is safe and has an acceptable toxicity profile. Furthermore, local control and enucleation rates are satisfactory and comparable to those of other series. Despite the fact that caution is required given the relatively short-term follow-up, the current approach has proven to be an effective and attractive noninvasive treatment for juxtapapillary choroidal

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  • Cited by (0)

    Rolina Al-Wassia and Alan Dal Pra contributed equally to this work.

    Conflicts of interest: none.

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