Background: A 31-GEP test is a validated prognostic tool for predicting the risk of metastasis in CM, classifying patients (pts) as Class 1 (low risk) or Class 2 (high risk). Here we report updated survival analysis from two clinical registry studies (NCT02355574/NCT02355587) designed to prospectively evaluate outcomes in patients for whom the GEP test was part of their clinical care. Methods: Eleven US dermatologic and surgical centers participated using IRB-approved protocols. Participants were CM pts ≥16 years old who had successful 31-GEP test results. Recurrence-free (RFS), distant metastasis-free (DMFS) and overall survival (OS) were assessed using Kaplan-Meier and Cox regression analysis. Results: At data censoring, 340 pts were accrued who had completed at least one follow-up visit. Median age was 58 years (range 18-87), 53.5% were male, median Breslow thickness was 1.2mm (range 0.2-12mm), 18.2% (62/340) were ulcerated, and 11.2% (38/340) had a positive sentinel lymph node (SLN). Median follow-up was 3.2 years for pts without an event. Six percent (16/265) of Class 1 pts had a recurrence compared to 33% (25/75) of Class 2 pts (p < 0.001). Three-year RFS was 96%, 91%, 80%, and 62% for Class 1A, 1B, 2A, and 2B, respectively (p < 0.001). Three-year DMFS was 97%, 93%, 84%, and 80% for Class 1A, 1B, 2A, and 2B, respectively (p < 0.001). Three-year OS was 98%, 90%, 96%, and 74% for Class 1A, 1B, 2A, and 2B, respectively (p < 0.001). Class 2 was an independent predictor of RFS and OS in multivariate analysis (respective HRs: 2.28 and 3.70, p < 0.05). Conclusions: Consistent with results from previous studies, this analysis demonstrates that the GEP test complements conventional staging and improves the ability to identify high-risk CM pts. These results support use of the test for guiding decisions related to follow-up, surveillance, and treatment in CM pts. Clinical trial information: NCT02355587