Low Dose 125I Brachytherapy and Transpupillary Thermal Therapy (TTT) for Small to Medium Size Choroidal Melanoma

To evaluate our institutional outcomes after treatment of small to medium size choroidal melanoma with low dose COMS brachytherapy. Single center, retrospective review of small to medium size choroidal melanoma < 5 mm in apical height managed from 2005-2019 with 125I brachytherapy at prescribed dose < 80 Gy, using a homogeneous dose calculation methodology. Ocular outcomes included visual acuity, presence of ocular radiation side effects, and local tumor recurrence. The Kaplan-Meier method was used to estimate overall survival, and metastasis rates were reported using cumulative incidence with death as a competing risk. Univariable associations were analyzed using Cox proportional hazards regression. Radiation statistics were calculated using Monte Carlo dosimetry. There were 146 patients included. Patient demographics and presenting tumor features are described in Table 1. Patients were treated with 125I plaque radiotherapy at median dose 65 Gy (IQR: 65-65 Gy) to depth of 5 mm, with additional transpupillary thermotherapy (TTT) at the time of plaque removal in 140 (95.9%) cases. Median follow-up was 6.7 years (IQR: 2.7-9.3 years). At final follow-up, median logMAR visual acuity was 1.1 (IQR: 0.4-2.0) with Snellen acuity 20/15-20/40 (20%), 20/50-20/160 (26%), and 20/200 or worse (54%). Radiation complications were as follows: cystoid macular edema in 54 (38%), radiation maculopathy in 71 (50%), non-proliferative radiation retinopathy in 53 (38%), proliferative radiation retinopathy in 20 (14%), and radiation papillopathy in 53 (38%). There were 11 patients who required subsequent pan-retinal laser photocoagulation (8%). Radiation dose did not appear to impact radiation maculopathy or retinopathy, but radiation papillopathy was significantly associated with point dose, maximum dose, and mean dose to the optic disc (p < 0.05). Local tumor control was achieved in 145 (99.3%) patients with recurrence in 1 (0.7%) patient 6.5 years after plaque. The 5-year cumulative incidence of distant metastasis was 7.2% with 5-year overall survival of 96.2%. Low dose 125I plaque radiotherapy with TTT provided high rates of local tumor control. Radiation maculopathy, retinopathy, and papillopathy were still observed even with reduced radiation apex dose. Future studies are warranted to determine rates of tumor control and ocular toxicity in low dose brachytherapy without TTT.Abstract 3687; TablePatient CharacteristicsMedian age61 years (IQR: 51-68 years)SexFemale 58%ComorbiditiesAtherosclerotic disease 44%Diabetes 18%Hyperlipidemia 45%Hypertension 49%Tumor CharacteristicsMedian logMAR visual acuity0.18 (IQR: 0.0-0.4)Snellen acuity20/15-20/40 68%20/50-20/160 29%20/200 or worse 3%Tumor dimensionsLargest basal diameter (IQR) 8.0 mm (IQR: 6.7-10.0 mm)Thickness (IQR) 2.0 mm (IQR: 2.0-2.0 mm)Secondary retinal detachment18%Subfoveal/subretinal fluid88% Open table in a new tab