Purpose
To determine whether gene expression profiling (GEP) is associated with rate of tumor regression following I-125 plaque brachytherapy for posterior uveal melanoma.
Methods
Retrospective review of of 83 patients with posterior uveal melanoma treated with I-125 plaque brachytherapy in which GEP class and 3-month post-radiation ultrasonographic tumor thickness were available. Recorded data included baseline patient and tumor characteristics and tumor thickness at 3-months after treatment. Statistical analysis was performed using T-test and Fischer’s exact test.
Results
GEP class assignment was class 1 in 83 (60.1%) and class 2 in 55 (39.9%) of patients. Mean patient age was 60.9 years for class 1 and 68.1 years for class 2 tumors (P=0.002). Mean initial tumor diameter was 13.0 mm for class 1 and 14.1 mm for class 2 tumors (P=0.02). Mean initial tumor thickness was 5.3 mm for class 1 and 6.1 mm for class 2 tumors (P=0.09). Mean reduction in tumor thickness at 3-month post-radiation 26.5% for class 1 and 13.0% for class 2 tumors (P=0.01). Complete tumor regression with flat residual tumor was observed for four class 1 tumors and no class 2 tumors.
Conclusions
Class 1 tumors exhibit more rapid early tumor regression than class 2 tumors following I-125 plaque radiotherapy. This observation may reflect molecular and/or immunologic differences between the two tumor classes.
Keywords: 744 tumors •
533 gene/expression •
639 pathology techniques