31-GEP (DecisionDx): a review of clinical utility and performance in a Mayo Clinic cohort

Background: Cutaneous melanoma (CM) is a significant health concern because of its high metastatic potential. Gene Expression Profile (GEP) testing, particularly the 31-GEP test (DecisionDx-Melanoma), has been increasingly used for risk stratification in CM patients. This study aimed to evaluate the clinical utility and performance of the 31-GEP test in a real-world setting.

Methods: Patients with CM who underwent 31-GEP testing from August 2014 to August 2022 at our institution were identified through searches of electronic health records. The study analyzed the influence of 31-GEP testing on clinical decision-making related to sentinel lymph node biopsy (SLNB), medical oncology referral, and postdiagnosis surveillance. Kaplan-Meier curves and Cox proportional hazard models were used to elucidate the test's performance, focusing on relapse-free survival (RFS) and melanoma-specific survival (MSS).

Results: The study included 65 CM patients. Dermatologists ordered more than 80% of 31-GEP tests. In 81.5% of cases, 31-GEP results did not alter standard clinical management. SLNB decisions were unaffected in 92% of patients with pre-SLNB 31-GEP results. Among patients with stage I-IIA melanoma, 25% of those with high-risk 31-GEP results were referred to medical oncology. Contrary to expectations, the rate of nodal metastasis was higher in low-risk than in high-risk 31-GEP cases. Survival analysis showed overlapping RFS and MSS curves between different 31-GEP classes, suggesting limited prognostic value.

Conclusions: The 31-GEP test has a limited impact on clinical management decisions and shows limited prognostic value.