Test identifies Stage I or II patients at high risk of metastasis
About 60,000 people are diagnosed each year with early stage, non-metastatic melanoma. While traditional staging provides valuable prognostic information, it misses many patients who develop metastatic disease. In fact, according to the American Cancer Society, 3% of Stage IA, and 9% of IB tumors will turn deadly within 5 years. In addition, 19% of Stage IIA, 30% of IIB, and 47% of IIC melanomas will likely prove fatal over a 5-year period.
The most accurate staging tool for stratifying metastatic risk, is the sentinel lymph node biopsy, or SLNB (McMasters, 2004; American Joint Committee on Cancer, 2010), yet 2 out of 3 patients who develop metastatic disease are identified as “node-negative” at diagnosis. These patients do not receive the increased surveillance and treatment options afforded those diagnosed at higher risk by current standards (Coit, et al, v.2, 2013).
To address the need for a more accurate predictor of metastatic risk, Castle Biosciences discovered, developed and completed validation for DecisionDx™-Melanoma. The gene expression profile (GEP) test is designed to identify high risk Stage I and II patients based on biological information from 31 genes within their tumor tissue.
With the additional tumor-specific information provided by the GEP test, physicians and patients are able to make more informed decisions about how aggressively to manage the disease.
For example, most Stage II patients today receive routine clinical skin and lymph node exams, and are not recommended for imaging such as brain or lung scans, or considered for adjuvant therapy options. If those Stage II patients were identified as having high risk tumor biology, their doctor might consider “upstaging” them for active systemic surveillance or referral to medical oncology for consideration of systemic drug therapy or clinical trials.
Similarly, some patients with Stage I melanoma will metastasize, yet they are treated as low risk. Stage I melanoma makes up the majority of all melanoma. If accurately identified as high risk, they too could be considered for more aggressive monitoring and treatment.
The DecisionDx-Melanoma test was validated in the largest biomarker study of its kind as an accurate, independent predictor of a patient’s metastatic risk—regardless of all other staging factors. Using archival tumor samples with long term clinical follow-up data, the GEP test correctly identified over 80% of Stage I and II patients who went on to metastasize. The study showed that the GEP test is a highly accurate and independent predictor of individual metastatic risk in Stage I and II disease (Gerami, Clinical Cancer Research, 2015).
The second validation study, published in the Journal of the American Academy of Dermatology (JAAD), and presented at the annual meetings of AAD and ASCO in 2014, further supported the accuracy of the GEP test. This study, which used archival tissue samples, showed that the GEP test significantly improved on the prognostic accuracy of sentinel lymph node biopsy (SLNB) in identifying patients at high risk of their cancer spreading. The GEP test was able to identify as high risk a large number of patients whose sentinel lymph node biopsy results did not indicate any increased risk, but who subsequently developed metastatic disease (Gerami, JAAD, 2015).