Establishing an evidence-based decision point for clinical use of the 31-gene expression profile test in cutaneous melanoma

Abstract

Treatment plans for cutaneous melanoma are based upon individual risk of recurrence. Decisions made post-diagnosis include recommendation for a sentinel lymph node biopsy (SLNB), followed by management decisions such as surveillance, frequency of follow-up, and interdisciplinary consultations including possible adjuvant therapy use. These have traditionally been guided by clinicopathologic factors, but discordance exists, as a substantial number of melanoma deaths occur in patients diagnosed with disease considered to be early stage by such factors, including a negative SLNB.  Molecular testing can be used to apply an objective approach that optimizes individualized patient care.  The 31-gene expression profile (31-GEP) test has been validated in nearly 1600 patients as an independent predictor of risk of recurrence, distant metastasis and death in Stage I-III melanoma and can guide SLNB decisions in patient subgroups, as demonstrated in 1421 patients.  While clinical use of the 31-GEP test has been adopted into routine practice, an evidence-based analysis of a decision point for use in thin, T1 tumors would be clinically useful.  To help define an appropriate population for 31-GEP testing, we evaluated changes in patient management, cumulative differential risk across Breslow thicknesses based on a large dataset, and 31-GEP subclass distribution in a clinically tested cohort. Based on this, appropriate use of the 31-GEP test for management decisions was found to be in cutaneous melanoma tumors ≥0.3 mm thick.