Abstract

DecisionDx-Melanoma (Castle Biosciences) is a commercial 31-gene expression profile test developed to guide melanoma management via stage-independent risk stratification. In this study, we evaluated ordering trends, patient and tumor characteristics, and test results from 250 cases at a large referral center between 2015 and 2023. There was a significant increase in test orders over the study period, rising from 11 in 2015 to 57 in 2023 (R² = 0.70, p ≤ 0.05). The cohort was 52% male and 48% female, with a mean age of 60.1 years. Sample types included shaves (80%), punches (14%), and excisional specimens (7%). Tumors were primarily on the trunk (41%), extremities (40%), and head/neck (18%). Breslow's thickness ranged from 0.1mm to 8.0mm, with a median of 0.6mm. Stage pT1 melanomas accounted for 78% of cases, followed by pT2 (15%), pT3 (5%), and pT4 (2%). Among 239 cases with known test results, 32 (13%) were classified as having increased or highest risk for recurrence/metastasis (Class 1B, 2A, or 2B). Of these cases, 6 (19%) were stage pT1 while 26 (81%) were stage pT2 or higher. Most tests were ordered by providers in community practices (60%), while 40% originated from academic settings. The findings in this study reflect the growing adoption of personalized genomic testing into clinical practice. Further study examining clinical outcomes of these patients in real-world settings may be of interest to establish best practices for utilization of this test.