Ultrasound Biomicroscopy Documented Anterior Uveal Melanoma Regression after Ruthenium-106 Plaque Therapy

Introduction: Ultrasound biomicroscopy (UBM) is the only widely used method for the evaluation of anterior uveal melanoma (AUM). Objective: Documentation of regression of AUM treated with ruthenium-106 (Ru-106) plaque types CCB and CCC using UBM. Methods: This single institution-based retrospective case series involved 10 Caucasian patients with AUM followed after brachytherapy with UBM from January 2014 until February 2019. The largest prominence of the tumor perpendicular to the sclera or the cornea (including scleral/corneal thickness) (D) and the largest basal dimension (B) were measured in millimeters with UBM for all patients prior to the brachytherapy and at 4-month interval follow-up. Tumor regression was calculated as a percentage of decrease in the initial D and B values. Results: The study involved 10 patients with a mean age of 64.4 years (yr) (range 46-80 yr). D ranged from 1.82 to 5.5 mm (median 2.99 mm) and B from 2.32 to 12.38 mm (median 4.18 mm). The apical radiation dose in all patients was 100 Gy. The median follow-up was 42.02 months. Regression for D was 21.11 +/- 13.66%, 31.09 +/- 14.66%, and 34.92 +/- 19.86% at 1st, 2nd, and 3rd year of the follow-up, respectively, while for B it was 21.58 +/- 16.05%, 28.98 +/- 17.71%, and 32.06 +/- 18.96%, respectively. Tumor recurrence was documented in 2/10 patients. Conclusion: The major regression of AUM, treated with Ru-106 plaque types CCB and CCC, was documented in the first 2 years after brachytherapy in our study group. In the following years, only minimal regression was documented that warns of the need for close monitoring and active search for local recurrences.