Abstract
Purpose :
To compare treatment outcomes after standard dose (70 Gy) proton radiation to lower dose (50 Gy) proton radiation in a large cohort of patients with small to medium tumors located near the optic nerve or fovea.
Methods :
We identified 1,017 patients diagnosed with uveal melanoma and treated with proton radiation at the Massachusetts Eye and Ear through December 2011. The cohort included patients who had small- to medium-sized melanomas (largest basal diameter <= 15 millimeters and tumor height <= 5 millimeters), located within 1 disc diameter of the optic nerve and/or fovea. 775 patients received 70 Gy and 242 patients received 50 Gy. Rates of vision retention, tumor recurrence, and survival were compared between the two dose groups, and the log rank test was used to identify significant differences.
Results :
At 5 years after treatment, 43.5% of patients in the 50 Gy group and 34.1% of those in the 70 Gy group had visual acuity of at least 20/200 (P=0.12). Some patients retained visual acuity of 20/40 or better: 5 year rates of retention were 18.8% and 13.1% in the low dose and standard dose groups respectively (P=0.06). Excellent local control of the tumor was observed in both dose groups (97.9% in the 50 Gy group and 98.5% in the 70 Gy group, P=0.18). Melanoma-mortality rates were similar in the 2 dose groups; 2.7% of patients in the 50 Gy group and 5.2% of patients in the 70 Gy group (p=0.94) had died of metastatic melanoma by 5 years after receiving therapy.
Conclusions :
The anticipated functional benefit of a radiation dose reduction from 70 Gy to 50 Gy was not observed in this cohort of patients with small to medium tumors near the optic nerve or fovea. However, local tumor control and survival were not compromised. Further dose reduction may be necessary to achieve improvements in functional outcomes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.