Enhanced Risk Stratification for Sentinel Lymph Node Biopsy in Head and Neck Melanoma Using the Merlin Assay (CP-GEP)

Sentinel lymph node biopsy (SLNB) for head and neck melanomas involves complex challenges due to intricate lymphatic networks and delicate anatomic structures. The Merlin Assay (CP-GEP), merging clinicopathologic data with gene expression profiling, offers a non-invasive method to identify patients who have a low risk for nodal metastasis, potentially sparing these low-risk patients from surgical procedures.

This study evaluated 250 clinically node-negative patients with stage I, II, or III melanoma from the Mayo Clinic and University Hospitals Cleveland Medical Center who had tumors in the head and neck region diagnosed between 2004 and 2021. All the patients underwent SLNB. The Merlin Assay, using the CP-GEP model, combines patient age at diagnosis, Breslow thickness, and gene expression of eight specific genes from the primary tumor to predict the risk of nodal metastasis.

The SLNB positivity rate was 14% overall, and CP-GEP predicted a possible 40.8% reduction in SLNB procedures with a negative predictive value (NPV) of 98%. For 215 SLNB-negative patients (5-year recurrence-free survival [RFS] of 76.9%, distant metastasis-free survival [DMFS] of 84.3%, and melanoma-specific survival [MSS] of 90.6%), CP-GEP improved risk stratification by identifying 100 patients as low risk with 5-year RFS of 86.1%, DMFS of 92.7%, and MSS of 95.3%. Among 167 T1-T2 patients, the SLNB positivity rate was 8.4%, and CP-GEP achieved an SLNB reduction rate of 56.3% with an NPV of 98.9%.

The Merlin Assay effectively categorizes head and neck melanoma patients by risk, enabling more accurate clinical decision-making regarding SLNB and follow-up evaluation, especially for early-stage melanoma patients.