Confirmatory Cytopathology and Potential Impact on the Predictive Value of Gene Expression Profiling in Patients With Uveal Melanoma

Purpose: To determine whether the availability of a cytopathology-confirming diagnosis is correlated with the prognostic accuracy of a gene expression profiling assay. Methods: A single-center retrospective review was performed of patients diagnosed with uveal melanoma who had a fine-needle aspiration biopsy and gene expression profiling before proton therapy from 2012 to 2020. The development of metastases was compared in patients with gene expression profiling and cytopathology (gene expression profiling+cytopathology group) and patients with gene expression profiling only (gene expression profiling only group). Results: Of 141 patients with gene expression profiling, 98 (69.5%) had cytopathology results and 43 (30.5%) did not. The median tumor thickness was greater in the gene expression profiling+cytopathology group (5.0 mm) than in the gene expression profiling only group (3.1 mm) (P = .0003). The distribution of gene expression profiling class in these 2 groups, respectively, was class 1A, 38 (38.8%) vs 20 (46.5%); class 1B, 20 (20.4%) vs 15 (34.9%); class 2, 40 (40.8%) vs 8 (18.6%). Class 1A tumors metastasized in 4 patients (10.5%) in the gene expression profiling+cytopathology group and 3 patients (15.0%) in the gene expression profiling only group. Class 1B tumors metastasized in 3 patients (15.0%) and 1 patient (6.7%), and class 2 tumors metastasized in 18 patients (45.0%) and 5 patients (62.5%) in these 2 groups, respectively. The median months from initial treatment to metastasis diagnosis within each gene expression profiling class for the gene expression profiling+cytopathology and gene expression profiling only groups, respectively, was class 1A, 36.7 vs 33.6 (P = .86); class 1B, 37.8 vs 68.6 (P = 1.0); class 2, 19.0 vs 15.8 (P = .70). Conclusions: We found no evidence that the lack of confirmatory cytology negatively affects the accuracy of gene expression profiling, and no significant differences were found in the overall rates of metastasis between patients with and patients without cytopathology or rates within each class of gene expression profiling.