Proton beam therapy leads to excellent local control rates in choroidal melanoma in the intermediate fundus zone

Purpose: To evaluate long-term outcomes of proton beam radiotherapy in the treatment of choroidal melanoma of the intermediate zone of the fundus.

Design: Retrospective interventional single-center study.

Methods: The study was a retrospective analysis with long-term follow-up of 62 patients with a minimum tumor-to-disc and tumor-to-fovea distance of 2 mm of choroidal melanoma in the intermediate zone of the fundus. Mean values of tumor prominence, largest basal diameter, and tumor distances to the optic disc and fovea were 7.6, 12.8, 5.2, and 4.6 mm, respectively. All patients were irradiated with a total proton dose of 60 cobalt gray equivalents.

Results: After proton beam radiotherapy, 71.0% of the patients received subsequent endoresection of the tumor. Only 18 patients (29.0%) did not require additional tumor resection and were analyzed as a separate group. For the total of patients, the median follow-up time was 70.3 months. The 5-year Kaplan-Meier rates of local tumor relapse, enucleation, and distant metastasis were 3.9%, 3.7%, and 13.4%, respectively. Cataract surgery was the most frequent secondary treatment in our cohort.

Conclusions: In this study we demonstrate the effectiveness of proton beam irradiation in tumor control and preservation of the globe in the analyzed patients. The rate of metastasis was not higher than previously described. Nevertheless, consecutive tumor surgery is frequently required to maintain the eye in patients with large-sized choroidal melanomas. In conclusion, proton beam radiotherapy allows preservation of the eye in mid-zone choroidal melanomas.