Castle Biosciences Publishes Studies on DecisionDx-SCC Test for High-Risk Cutaneous Squamous Cell Carcinoma

Castle Biosciences has announced the publication of two studies related to its DecisionDx-SCC test, which is used to predict the risk of local recurrence and metastasis in patients with high-risk cutaneous squamous cell carcinoma. The studies found that the test significantly stratified both local recurrence and metastatic risk, with three-year survival rates decreasing progressively across risk classes. The test results, combined with immunosuppression and perineural invasion, were significant predictors of local recurrence. The test accurately predicted risk above the 10% and 20% thresholds where clinicians would recommend surveillance imaging and treatment, respectively.

Castle Biosciences, Inc. (Nasdaq: CSTL) has announced the publication of two studies related to its DecisionDx-SCC test, which aims to predict the risk of local recurrence and metastasis in patients with high-risk cutaneous squamous cell carcinoma (SCC). The studies, published on August 25, 2025, provide compelling evidence of the test's ability to enhance risk stratification and guide treatment decisions.

The first study, led by Désirée Ratner, M.D., and colleagues, demonstrated that DecisionDx-SCC significantly stratified both local recurrence and metastatic risk among 414 NCCN high-risk SCC patients who underwent Mohs resection. The test showed three-year survival rates decreasing progressively across risk classes, with local recurrence-free survival (LRFS) at 95.3% for Class 1 (low risk), 85.5% for Class 2A (higher risk), and 71.4% for Class 2B (highest risk), with P=0.001. Metastasis-free survival (MFS) was 97.1%, 89.3%, and 57.1% for the respective classes, with P0.001. In contrast, traditional staging systems failed to significantly stratify LRFS and MFS.

The second study, conducted by a group of clinicians, confirmed that DecisionDx-SCC results aligned with treatment decision-making thresholds for adjuvant radiation therapy (ART) and surveillance imaging. Among 244 surveyed clinicians, ART was recommended for patients with ≥20% risk of local recurrence or metastasis, and surveillance imaging for patients with ≥10% risk of metastasis. DecisionDx-SCC Class 2A results accurately predicted risks above the 10% threshold, while Class 2B results predicted risks above the 20% threshold.

These studies suggest that DecisionDx-SCC has the potential to address the clinical need for better risk stratification tools, enabling risk-aligned treatment decisions and potentially improving outcomes within established NCCN treatment pathways.

References:
[1] https://ir.castlebiosciences.com/news/news-details/2025/New-Evidence-Published-Supporting-Use-of-DecisionDx-SCC-Test-in-Guiding-and-Improving-Treatment-Pathway-Decisions-in-NCCN-High-Risk-Cutaneous-Squamous-Cell-Carcinoma/default.aspx
[2] https://ir.castlebiosciences.com/news/news-details/2025/New-Evidence-Published-Supporting-Use-of-DecisionDx-SCC-Test-in-Guiding-and-Improving-Treatment-Pathway-Decisions-in-NCCN-High-Risk-Cutaneous-Squamous-Cell-Carcinoma/default.aspx