Clinical Summary

Up to 88% of sentinel lymph node biopsies (SLNBs) are negative. The 31-gene expression profile (31-GEP) test can help identify patients with a low risk of SLN metastasis who can safely forego SLNB. The 31-GEP classifies patients as low (Class 1A), intermediate (Class 1B/2A), or high risk (Class 2B) for recurrence, metastasis, and SLN positivity. The integrated i31-SLNB combines the 31-GEP risk score with clinicopathologic features using a neural network algorithm to personalize SLN risk prediction.  

Patients from a single surgical center with 31-GEP results were included (n=156). An i31-SLNB risk prediction <5% was considered low risk of SLN positivity. Chi-square was used to compare SLN positivity rates between groups.  

DecisionDx-Melanoma outperformed AJCCv8 in identifying patients who should undergo an SLNB

• Patients with T1-T2 tumors and i31-SLNB positivity risk >10% had a SLN positivity rate of 33.3%, outperforming AJCCv8 in identifying patients who should undergo an SLNB.
• Using the i31-SLNB to guide SLNB decisions could have significantly reduced the number of unnecessary SLNBs by 19.2% (30/156, p<0.001) for all patients, and 33% (30.91, p<0.001) for T1-T2 tumors.
• Patients considered low risk by the i31-SLNB score had a 0% (0/30) SLN positivity rate compared to 31.9% (30/94, p<0.001) positivity rate in those with >10% risk.

The  i31-SLNB identified patients with <5% risk of SLN positivity who could safely forego SLNB. Combining the 31-GEP with clinicopathologic features for a precise risk estimate can help guide risk-aligned patient care decisions for SLNB to reduce the number of unnecessary SLNBs and increase the SLNB positivity yield if the procedure is performed.