Gamma-knife-based stereotactic radiosurgery for medium- and large-sized posterior uveal melanoma.

BACKGROUND: This study investigated the use of gamma-knife-based stereotactic radiosurgery (GKRS) for medium- and large-sized posterior uveal melanoma treatment.
METHODS: We assessed 50 eyes from 50 consecutive patients with uveal melanoma who were treated with GKRS. All tumors met the criteria for medium- and large-sized uveal melanomas. Patients underwent a single session treatment under local anesthesia; the prescribed radiation dose at the tumor periphery was standardized to 30 Gy at the 50 % isodose field for all patients. The main outcomes were local tumor control, eye retention, and survival rates.
RESULTS: The median follow-up time was 40 months (16-78 months). The baseline mean tumor diameter was 10.3 mm (7.1-15.7 mm) and the apical tumor height was 8.7 mm (4.1-16.8 mm). After treatment, the mean tumor diameter was 8.7 mm (5.5-12.0 mm) and the tumor height was 6.2 mm (0.5-11.2 mm). Changes in both tumor height and diameter were statistically significant (p < 0.001). The tumor control rate was 90 %, and the eye retention rate was 82 %. A total of nine patients (18 %) developed metastasis, and seven (14 %) died due to metastasis during follow-up. Cataracts (34 %) and radiation maculopathy (30 %) were the most frequent complications, and 14 % of patients developed neovascular glaucoma. Visual acuity (VA) decreased significantly after treatment (p < 0.0001).
CONCLUSION: Treatment using low doses of GKRS, (30 Gy) is an eye-sparing outpatient option for patients with medium- or large-sized posterior uveal melanomas who are not eligible for brachytherapy or particle therapy. Complications, particularly impaired VA, should be taken into consideration.