Castle Biosciences’ DecisionDx-Melanoma i31-SLNB test classified low-risk melanoma patients with a 2.6% SLN positivity rate versus 5.8% for the MIA nomogram in a 912-patient prospective study. The i31-SLNB also showed superior discriminative accuracy (AUC 0.74 vs. 0.61).
The prospective, multicenter DECIDE study enrolled 912 cutaneous melanoma patients across multiple centers to directly compare the DecisionDx-Melanoma i31-SLNB result with the Melanoma Institute Australia nomogram for SLN positivity prediction.
Patients classified as low risk by i31-SLNB had a 2.6% observed SLN positivity rate versus 5.8% by the nomogram; discordant classifications yielded 2.8% versus 11.5% positivity, and overall discriminative performance improved (AUC 0.74 vs. 0.61; p=0.001).
By accurately identifying patients below the 5% NCCN threshold for SLNB avoidance and those exceeding 10% risk, the i31-SLNB result can reduce unnecessary surgeries and guide personalized biopsy recommendations in melanoma staging.
Strengthened prospective evidence may drive broader adoption of DecisionDx-Melanoma testing, supporting revenue growth and reinforcing Castle Biosciences’ market position as the test has been ordered over 240,000 times and clinically validated in over 10,000 samples.
