This prospective cohort study (DECIDE study) compared the i31-SLNB (integrated 31-gene expression profile) to the MIA nomogram for predicting sentinel lymph node (SLN) positivity in 430 SLN-assessed patients with T1–T4 cutaneous melanoma.
The i31-SLNB had a significantly higher AUC than the MIA nomogram (0.74 vs. 0.61; p=0.001). When predicting <5% SLN positivity risk, observed positivity was 2.6% for i31-SLNB (NPV 97.4%, 95% CI 94.2–100.0%) vs. 5.8% for MIA (NPV 94.2%, 95% CI 88.1–98.7%). In head-to-head conflicts, observed positivity was 1.9–2.8% below i31-SLNB thresholds and 11.5–25.8% above them.
- Only patients who underwent SLNB were analyzed (n=430 of 912 enrolled), potentially introducing selection bias. - The MIA nomogram uses only clinicopathologic variables, while i31-SLNB integrates gene expression, making direct comparison inherently asymmetric. - Long-term survival outcomes were not reported; the study focused solely on SLN positivity prediction.
The i31-SLNB test more accurately identifies melanoma patients at low risk of SLN positivity than the MIA nomogram, and may help avoid unnecessary SLNB in appropriately selected patients. Clinicians can consider using it alongside standard clinicopathologic assessment when counseling patients about SLNB.
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