Hypofractionated stereotactic photon radiotherapy of posteriorly located choroidal melanoma with five fractions at ten Gy--clinical results after six years of experience

Abstract

Purpose: To evaluate long-term safety and efficacy of hypofractionated stereotactic photon radiotherapy with 5 five fractions at 10 Gy each in patients with centrally located choroidal melanoma.

Materials and methods: Ninety-one patients with centrally located choroidal melanoma were treated stereotactically at a linear accelerator with 6 MV photon beams with 5 fractions at 10 Gy each. Examinations were performed at baseline and every 3 months in the first 2 years, then every 6 months until 5 years and yearly thereafter. Median follow-up was 37.8 months (IQR 19.2-49.9). They included visual acuity assessment, routine ophthalmological examinations with fundoscopy, echography for measurement of tumor dimensions, medical examinations and, if necessary, fluorescein angiography.

Results: Initial tumor base diameters, height and volume were 11.20mm (IQR 9.10-13.70), 9.80 mm (IQR 7.80-11.70), 4.53 mm (IQR 3.33-6.43) and 253.8mm(3) (IQR 127.5-477.0). Local tumor control and eye retention rates were 97.7% and 86.4% after 5 years, respectively. Eight patients developed metastatic disease and 3 of them died due to metastatic disease during the follow-up period. Median visual acuity decreased from 0.67 initially to 0.05 at the last individual follow-up (p<0.001). The most common toxicities (any grade) were radiation retinopathy (n=39), optic neuropathy (n=32), radiogenic cataract (n=21), neovascular glaucoma (n=15) and dry eye syndrome (n=10). The 5 year probabilities to remain free of these side effects (any grade) were 26.0%, 45.4%, 55.4%, 72.6% and 80.5%, respectively. The most important prognostic factors for toxicities were the largest tumor base diameter, tumor height and tumor distance to the optic disk.

Conclusion: Hypofractionated stereotactic photon radiotherapy with a total dose of 50 Gy delivered in 5 fractions is a highly effective treatment option in patients with centrally located choroidal melanoma and has a moderate toxicity profile.

Keywords: Choroidal; Hypofractionated stereotactic photon; Linear accelerator; Melanoma; Radiotherapy.