DecisionDx-SCC test stratifies skin cancer metastatic risk, guides treatment

Key takeaways:

• Patients classified with highest risk who were treated with ART had a 50% decrease in metastatic disease progression.
• DecisionDx-SCC helped rule out the clinical need for ART in those with low risk.

The DecisionDx-SCC test successfully identified which patients with cutaneous squamous cell carcinoma would most likely benefit from adjuvant radiation therapy, according to a study.

Using individual patients’ tumor biology, the DecisionDx-SCC (Castle Biosciences) is a 40-gene expression profile test that stratifies the risk of metastasis in patients with cutaneous squamous cell carcinoma (SCC) who also have one or more National Comprehensive Cancer Network high-risk factors.

After evaluating the tumor, the tool classifies patients into three groups: Class 1, Class 2A or Class 2B, which indicate low, higher or highest metastatic risk, respectively.

“Some patients with high-risk SCC are eligible for adjuvant radiation therapy (ART) once their primary tumor has been removed; however, determining which patients should seek treatment is complicated and involves weighing numerous pros and cons against the risk of the patient’s cancer returning,” Emily S. Ruiz, MD, MPH, FAAD, a dermatologist and Mohs micrographic surgeon at Brigham and Women’s Hospital in Boston, associate professor of dermatology at Harvard Medical School and the lead author of this study, said in a Castle Biosciences press release.

The study, which was published in Future Oncology, included 399 patients with a total of 423 SCC tumors. DecisionDx-SCC was used to analyze the 5-year metastasis-free survival of each patient as well as the tumor’s projected time to metastasis.

Findings showed that patients who received a DecisionDx-SCC Class 2B result who were treated with ART had a 50% decrease in metastatic disease progression, according to the release. Patients with Class 2B tumors that went untreated had a 60% median disease progression rate at 5 years post-diagnosis, whereas those treated with ART had a 0% rate.

While the study showed no difference in disease progression rates when comparing ART-treated and untreated patients with a Class 1 rating, using DecisionDx-SCC helped rule out the clinical need for ART in this low-risk population, according to the release.

Only a modest benefit was observed for those with Class 2A ART-treated tumors, with the median disease progression being 30.5% in those were untreated and 12.5% in those ART-treated.

“In this study, we were successful in validating, in an independent SCC patient cohort, that DecisionDx-SCC can objectively inform these challenging decisions by identifying patients for whom ART would be beneficial, as well as those who may be best served by avoiding it,” Ruiz concluded.

Reference:

• Study confirms the ability of Castle Biosciences' DecisionDx-SCC test to predict likelihood of benefit from adjuvant radiation therapy in patients with high-risk cutaneous squamous cell carcinoma. https://www.businesswire.com/news/home/20240905034579/en/Study-Confirms-the-Ability-of-Castle-Biosciences-DecisionDx%C2%AE-SCC-Test-to-Predict-Likelihood-of-Benefit-from-Adjuvant-Radiation-Therapy-in-Patients-with-High-Risk-Cutaneous-Squamous-Cell-Carcinoma. Published Sept. 5, 2024. Accessed Sept. 5, 2024.