Castle study shows DecisionDx gene test predicts melanoma risks better than staging alone

Castle Biosciences presented new data from a study of its DecisionDx melanoma test, showing it improved predictions of individual recurrence risk and sentinel lymph node positivity by measuring the expression of 31 genes from the primary tumor.

The study evaluated impacts on risk assessment for 690 stage I-III melanoma patients compared to the American Joint Committee on Cancer’s population-based staging system, which considers tumor size and the numbers of metastases and affected lymph nodes. The results showed combining the test and AJCC staging significantly improved risk stratification.

Using staging alone, patients with stage I melanoma have an estimated 98% melanoma-specific survival rate of five years following diagnosis. However, patients in the stage I group that were found to have the highest risk, as determined by the DecisionDx test, had an 89.5% five-year survival, similar to risk estimates for stage IIb disease.

“Accurate risk assessment is important for clinical decision-making. These results show that use of the DecisionDx-Melanoma test can further inform clinicopathologic staging and help guide patient management choices,” Castle Biosciences Chief Medical Officer Federico Monzon, M.D., said in a statement. The study was presented at the DERM2018 NP/PA CME conference in Las Vegas, Nevada.

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“Incorporating DecisionDx-Melanoma test results can drive improvements in follow-up and surveillance planning as well as sentinel lymph node biopsy discussions,” Monzon added.

Meanwhile, in stage III melanoma with a typical five-year survival rate of 77% using AJCC estimates, the genomic test more accurately stratified those patients, drawing lines between a lower-risk group with a 94.8% survival rate and a higher-risk group with a 61.2% survival rate.

In addition, the study assessed the test’s technical reliability in over 17,100 orders, demonstrating 98.3% reporting success for samples with adequate tumor content.