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Kisha Piggott, Cynthia Montana, Kathryn Trinkaus, Kumar Rao; Plaque radiotherapy induced uveal melanoma regression rates based on gene expression profile. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3628.
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© ARVO (1962-2015); The Authors (2016-present)
Uveal melanoma gene expression profile (GEP) testing predicts metastatic risk based on two main tumor classes. It is hypothesized that the more malignant class 2 tumors should demonstrate more rapid regression responses to radioactive plaque therapy than class 1 tumors. Prior studies have shown mixed results regarding GEP correlated melanoma treatment regression rates. This study aims to determine whether gene expression profile correlates with differential tumor regression rates following Iodine-125 brachytherapy.
Clinical data of patients with posterior uveal melanoma and gene expression profiling performed on tumor biopsy samples taken at the time of episcleral plaque radiotherapy were retrospectively reviewed. In addition to baseline tumor characteristics including class, location and ultrasonographic tumor thickness, serial tumor height measurements documented at 3 ,6,9,12, 24 months and most recent follow up were recorded. Tumor regression rates were analyzed based on pre-operative tumor thickness. Statistical analysis was performed using a linear repeated measures model.
Of the total 193 patients studied, 122 (63%) tumors were identified as class 1 and 71 (37%) tumors as class 2 based on gene expression profile. Overall median follow up time was 46 months (range 14 to 96 months), and in the first 12 months tumor thickness decreased at a rate of 0.024mm per year (p < .0001). Mean patient age was 49.4 and 67.3 years in the class 1 and 2 groups respectively. Mean initial tumor thickness was 5.14mm for class 1 tumors and 5.61mm for class 2 tumors. Mean reduction in tumor thickness was 22.5% for class 1 and 13.98% for class 2 tumors at 3 months (p=.073). Mean reduction at 46 months was 52.97% and 44.29 % for class 1 and class 2 tumors respectively (p=0.34).Complete tumor regression to 0mm occurred in 4.09 % of the class 1 and 0% the class 2 tumors at 9 months. Secondary enucleation was required in 8.2% of the class 1 and 14.2 % of class 2 tumors.
This study showed at the earliest follow up of 3 months there is a differential but statistically non-significant radiotherapy induced tumor thickness reduction in class 1 vs class 2 posterior uveal melanomas. Subsequent time points showed a lack of correlation between tumor regression rates and gene expression profile following Iodine-125 brachytherapy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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