Understanding and Utilizing DecisionDx-Melanoma ® A Q&A With J. Michael Guenther, MD, Surgical Oncologist, St. Elizabeth Physicians, Edgewood, KY THE DERMATOLOGY DIGEST (TDD): What is the DecisionDx-Melanoma test? J. MICHAEL GUENTHER, MD: It is a test that provides prognostic information to guide management decisions for patients with cutaneous melanoma. The test is a second-generation prog-nostic tool that integrates the original 31-gene expression pro-file (31-GEP) test with clinicopathologic staging factors to give an individualized assessment of a patient’s risk of recurrence and/or metastasis and the likelihood of sentinel lymph node biopsy (SLNB) positivity. The 31-GEP test analyzes RNA in tissue from a primary melanoma for under-or overexpression of genes that provide information predictive of the tumor’s biological behavior. The clinicopathologic factors assessed include Breslow thickness, ulceration, mitotic rate, SLN status, age, and tumor location. The test report includes a class result (1A, 1B, 2A, or 2B) deter-mined from the 31-GEP score that informs the risk of recur-rence and likelihood of SLN positivity. Integrating the 31-GEP score and the patient’s clinicopathologic factors (i31-GEP), the report also provides a personalized likelihood of SLN positivi-ty and personalized risk of recurrence estimates for 5-year rate of melanoma-specific survival, distant metastasis-free survival, and recurrence-free survival. Before DecisionDX-Melanoma became available, we had no tools for predicting tumor behavior and patient outcomes. Based on the information in the DecisionDx-Melanoma re-port, clinicians are better able to identify patients with high-risk disease and decide about treatment or appropriate careful surveillance to enable early detection of metastasis/recurrence and intervention that is more likely to be successful when metastatic disease burden is low. The DecisionDx-Melanoma report also identifies patients with low-risk disease who can safely forego SLNB. The information from the DecisionDx-Melanoma test gives insight into the future. As an analogy, imagine having the ability to act on knowledge of when and where a hurricane will hit or how the stock market will perform. Similarly, guided by the DecisionDx-Melanoma test, clinicians can make good decisions for patients, knowing how the individual’s tumor will behave. TDD: How does the DecisionDx-Melanoma test identify patients who can safely avoid SLNB? DR. GUENTHER: As demonstrated by results of the DECIDE study, patients whose predicted risk for a positive SLN is <5% can safely avoid undergoing this costly and invasive procedure. 1 DECIDE is a prospective study including patients with cutaneous melanoma being considered for SLNB. Within the study cohort, 35 patients with T1-T2 tumors and an i31-GEP predicted risk of SLN positivity of <5% underwent SLNB. None of those 35 patients had a positive SLN. In addition, the study found that all 68 patients in the lowest-risk 31-GEP Class category (Class 1A) were free from recurrence after three years of follow-up. Studies show that the positivity rate for patients who undergo SLNB for cutaneous melanoma is only about 12%, which means that 88% of the time the SLNB is negative. Applying the result of the DecisionDx-Melanoma test to identify pa-tients who can safely avoid SLNB spares a lot of patients from undergoing the procedure and saves a lot of money. TDD: How does DecisionDX-Melanoma work? DR. GUENTHER: The original 31-GEP test was evaluated in pro-spective studies and was shown to accurately classify patients into qualitative categories (low, intermediate, high) describing risk of SLNB positivity and recurrence. That is powerful in-formation that no test before was able to provide successfully. Integration of the clinicopathologic factors allowed precise predictions of an individual’s risk for spread to the SLN and risk of recurrence at any point in time. TDD: Why is the information provided by the DecisionDX-Melanoma test so important? DR. GUENTHER: The biology and clinical behavior of cutaneous melanoma is highly variable. The tumor can regress sponta-neously, grow, or spread at different rates, or recur after being dormant for years. Understanding a melanoma’s malignant po-tential is critical information for guiding patient care decisions. TDD: How should I manage patients identified as high-risk by DecisionDx-Melanoma but who are node negative? DR. GUENTHER: The emphasis on management for such patients | 1 November/December 2024 Supplement
The Dermatology Digest Innovations in Personalized Medicine November/December 2024 Supplement: Page 1
