# DecisionDx-SCC

Source: https://onco.cc/drugs/decisiondx-scc/  
OnCo record `decisiondx-scc` (Test). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A tissue test for high-risk squamous cell skin cancer that measures 40 genes to estimate the chance of spread; Medicare does not cover it.

## Summary

Castle Biosciences describes "a qRT-PCR assay of 6 control and 34 discriminant genes (40 in total)" for cutaneous squamous cell carcinoma with at least one high-risk feature. In its validation, three-year metastasis-free survival was 91.4, 80.6 and 44.0 per cent for classes 1, 2A and 2B (Wysong 2021). Medicare's Palmetto MolDX policy L39583 states that "Current molecular biomarker tests that risk stratify individuals with cutaneous squamous cell carcinoma (cSCC) are non-covered by this contractor".

## Fields

- Kind: Test
- Status: emerging
- Last checked: 2026-11-04
- Also known as: 40-GEP; 40-gene expression profile
- Tags: test; rna
- Brand: DecisionDx-SCC
- Modality: Gene-expression prognostic assay (40-gene RT-PCR, cutaneous squamous cell carcinoma)
- Mechanism: Quantitative RT-PCR of 34 discriminating and 6 control genes in the primary tumour assigns class 1, 2A or 2B risk of metastasis.

## Sources

- Castle Biosciences: DecisionDx-SCC: https://www.castlebiosciences.com/tests/prognostic/decisiondx-scc/how-it-works
- CMS LCD L39583: MolDX: Molecular Biomarker Testing for Risk Stratification of Cutaneous Squamous Cell Carcinoma: https://www.cms.gov/medicare-coverage-database/view/lcd.aspx?lcdid=39583

## Connected records

- cancers: [Cutaneous squamous cell carcinoma](https://onco.cc/cancers/cutaneous-scc/)
- technologies: [Gene-expression prognostic assays](https://onco.cc/technologies/gene-expression-prognostic-assays/)
- companies: [Castle Biosciences](https://onco.cc/companies/castle-biosciences/)
- key papers: [Validation of a 40-gene expression profile test to predict metastatic risk in localized high-risk cutaneous squamous cell carcinoma](https://onco.cc/key-papers/paper-wysong-40-gene-cutaneous-scc-j-am-acad-dermatol-2021/)

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