How It Works

Guides risk-aligned melanoma care

DecisionDx-Melanoma, is a proprietary gene expression profile (GEP) test that uses an individual patient’s tumor biology to predict the risk of metastasis or recurrence, as well as the risk of sentinel lymph node positivity, independent of traditional staging factors. DecisionDx-Melanoma utilizes the genetic information within a patient’s tumor biology, providing actionable results to better inform and guide personalized management decisions in one comprehensive report. DecisionDx-Melanoma’s personalized risk assessments can help providers to improve patient outcomes.

More biological insight, better informed decisions


  • 31 genes
  • 28 discriminating and 3 endogenous control genes


Tumor biology and traditional clinicopathologic staging factors with independently validated algorithms  


Two key clinical questions:

  • risk of sentinel lymph node positivity
  • risk of recurrence and/or metastasis

DecisionDx-Melanoma testing process

DecisionDx-Melanoma is performed in Castle Biosciences’ CLIA certified, CAP-accredited and NY state approved laboratory using formalin-fixed, paraffin embedded (FFPE) primary tumor tissue from either a biopsy or excision.

Graphic of a microscope

Tissue biopsy submitted

Tissue blocks or slides from the primary tumor tissue biopsies are sent to our laboratory for testing.

Graphic of RNA

RNA/DNA preparation

Once tissue is received in our laboratory, RNA is isolated from the tissue and converted to cDNA. The cDNA for each of the 31 genes is amplified and the gene signature recorded. 

Graphic of DNA signature under a microscope

Signature interpretation

Using an independently validated algorithm, the individual patient's gene expression signature is assessed and a class score is provided. 

Graphic of specimens for analysis

DecisionDx-Melanoma reporting

One comprehensive report provides three important pieces of information: 

  • Class Score (Class 1A, Class 1B/2A, Class 2B)
  • Individual risk of SLN positivity (i31-SLNB)
  • Individual risk of recurrence (i31-ROR)

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A comprehensive report


DecisionDx-Melanoma is the first and only gene expression profile, molecular risk stratification test designed to deliver three personalized risk assessments in one easy-to-interpret result: class score, individual risk of recurrence (ROR) and individual risk of sentinel lymph node biopsy (SLNB) positivity.

31-GEP Class Score: 
DecisionDx-Melanoma quantifies the expression of 31 genes from the patient’s primary tumor using RT-PCR and uses a validated algorithm to provide a class score predicting a patient’s individual risk of recurrence and/or metastasis within 5 years.

i31-ROR and i31-SLNB: 

DecisionDx-Melanoma integrates the 31-GEP class score with significant clinical and pathological features to provide precise risk predictions informing two key clinical questions:

  • i31-ROR: Personalized risk of recurrence and/or metastasis
  • i31-SLNB: Personalized likelihood of SLNB positivity


Graphic of the DecisionDx Melanoma test report

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