New data from the prospective, multicenter DECIDE study demonstrates that the DecisionDx-Melanoma gene expression profile (GEP) test can safely guide clinicians in identifying melanoma patients who can forgo sentinel lymph node biopsy (SLNB) without compromising clinical outcomes.
The study, recently published in Cancer Medicine, found that patients with cutaneous melanoma and a Class 1A result from the 31-gene expression profile (31-GEP) test had a 100% 3-year recurrence-free survival rate, even when SLNB was not performed. These findings suggest a pathway to reduce unnecessary surgical procedures while maintaining excellent patient outcomes.
Refining Risk Stratification in Melanoma Management
The DecisionDx-Melanoma test, developed by Castle Biosciences, analyzes the expression of 31 genes within primary melanoma tumors to predict both sentinel lymph node positivity risk and likelihood of recurrence or metastasis.
Dr. J. Michael Guenther, lead author of the study and surgical oncologist, highlighted the test's significance: "Only about 12% of patients undergoing SLNB actually have positive nodes, highlighting the need for a more selective approach."
The test is particularly valuable for patients whose risk for positive SLNB falls between 5% and 10% based on traditional clinical and pathological factors. By integrating molecular data with these factors, the test enables more personalized decision-making.
DECIDE Study Results Validate Clinical Utility
Among 130 patients identified as low risk for SLN positivity using the DecisionDx-Melanoma test, none experienced melanoma recurrence at the time of last follow-up. In this cohort, 48.5% underwent SLNB, yielding a positivity rate of only 3.2%, while 51.5% were managed without SLNB.
"The test can accurately identify patients who have a less than 5% risk of having a positive sentinel lymph node biopsy at the time of diagnosis, who can be counseled about that risk," explained Dr. Matthew Goldberg, Senior Vice President, Medical at Castle Biosciences.
The study population classified as low risk had a median age of 65 years and median Breslow thickness of 0.9 mm. Tumor staging included 43.1% with T1b tumors, 33.1% with T1a, and 22.3% with T2a.
Clinical Implementation and Workflow Integration
From a practical standpoint, integrating the DecisionDx-Melanoma test into clinical workflows has become increasingly streamlined. Test results are typically available within 4 to 5 working days after a melanoma sample is received, making it an efficient addition to the care pathway.
"It took a while to overcome resistance to the way we always did things," Dr. Guenther admitted. "But I think the data speaks for itself. The DECIDE study is almost a perfect template for how this works in clinical practice."
Economic and Clinical Impact
Both experts emphasized the broader implications of the DecisionDx-Melanoma test, particularly in terms of reducing unnecessary surgeries and associated costs.
"The less unnecessary surgery we do, the better," Dr. Guenther noted, highlighting the substantial cost savings and reduced morbidity associated with avoiding unnecessary SLNBs.
The test has been evaluated in over 10,000 patient samples and supported by more than 50 peer-reviewed publications. Since its clinical launch, it has been ordered approximately 191,800 times (as of December 31, 2024).
Advancing Precision Medicine in Melanoma Care
Dr. Goldberg views the DecisionDx-Melanoma test as part of a larger movement toward precision medicine in oncology.
"This is an exciting moment for precision medicine," he said. "The challenge is: Can we do better than our histopathologic correlates? Can we do better than staging to refine our engine of prognosis for the benefit of the patients that we care for in the clinic?"
These findings build on previously published data from the DECIDE study, which showed that the DecisionDx-Melanoma test results influenced 85% of SLNB decisions. Additional findings published in the World Journal of Surgical Oncology demonstrated that substantial proportions of T1 and T2 patients could potentially have avoided SLN biopsy without compromising diagnostic accuracy.
As research continues, both experts remain invested in studying long-term outcomes in low-risk patients and further refining the integration of clinical-pathological data with gene expression profiling to advance personalized melanoma care.
