Frequently Asked Questions

What is DecisionDx-Melanoma?
DecisionDx™-Melanoma is a gene expression profile (GEP) test that tells you how likely your melanoma is to metastasize, or spread, based on the biology of your individual tumor. The test was specifically designed to identify the Stage I and II patients whose tumor biology suggests they are at higher or lower risk of metastasis than their stage might indicate.


What are the possible results from DecisionDx-Melanoma testing and what do they mean?
The DecisionDx-Melanoma test uses sophisticated technology to measure the “expression” or activity of specific genes within a tumor known to play a role in metastasis. The gene expression profile test will categorize your cancer as either Class 1 or Class 2.

The Class 1 signature is associated with low risk of metastasis (3%) within 5 years. Class 2 has a high risk (69%) within the same time period.


I’ve heard of “staging” as a way to determine my prognosis and treatment. How does DecisionDx-Melanoma compare?
Traditional methods of determining your prognosis such as AJCC staging are based on physical and histological (microscopic) features of the tumor such as its thickness, whether the cancer has spread to nearby lymph nodes, and its mitotic rate, which is the portion of cells that are actively dividing. While staging provides valuable prognostic information, its risk categories (Stages I-IV) are based on “group” risk—derived from studies of the outcomes of large groups of patients whose cancer shared similar characteristics.

The DecisionDx-Melanoma gene test was developed to go beyond the “group” risk of staging to provide information about a patient’s “individual” risk, based on their tumor biology. When used in combination with staging, the gene test’s results allow doctors and their patients to make more informed choices about monitoring and treatment.


We know that a certain percentage of the 60,000 patients diagnosed this year with Stage I or II cutaneous melanoma will eventually develop metastatic disease. How can this be explained?

Melanoma, like many other cancers, can spread either through the lymphatic system or through the hematogenous (blood) system. Traditional staging is based, in part, on presence of cancer cells in the lymph node(s) but is unable to account for metastasis that occurs through the hematogenous pathway or for lymphatic spread that may not show up as positive in the sentinel lymph node.

Now, through advances in personalized medicine, gene tests such as DecisionDx-Melanoma can evaluate a tumor’s individual biology to better predict how it will behave, regardless of the pathway by which it may spread.


How is DecisionDx-Melanoma performed?

As you know, your melanoma was diagnosed through a biopsy or surgical excision. This tumor specimen was preserved using formalin and placed in a wax (paraffin) block for further examination. By law, this block is to be saved (stored). Your doctor simply orders the DecisionDx-Melanoma test, and Castle Biosciences will request that the laboratory prepare slides of your tumor and send to us for processing. At this point, we assume that most biopsies, or tumor tissue contained within a wide excision, will contain an adequate number of melanoma cells for us to perform the DecisionDx-Melanoma test. If there are not enough cells, then we will inform your doctor that we will not be able to perform the test.

We typically send results of the test to your doctor within two to three weeks of receiving the tumor sample.


How can I get the test?
The DecisionDx-Melanoma test can only be ordered by a licensed physician or other appropriate healthcare provider.

As the test is new, your doctor may not be aware of the test. Please call, or have your doctor call our customer service group at 866-788-9007. You may also email us at

Will I still be able to have the test done if I was diagnosed several years ago?

For patients diagnosed up to 3 years previously, the testing can be routinely processed. For patients diagnosed between 3-5 years prior to testing, a phone call should be placed by the physician’s office to Castle for specific case discussion. For patients diagnosed greater than 5 years previously, the information obtained from this testing would not likely prove useful as the test was designed to predict metastatic risk at 5 years.

How are the test results from DecisionDx-Melanoma used?

While the test cannot, at this point, guide your doctor toward a specific treatment, results from the DecisionDx-Melanoma test provide important information which may help you and your doctor determine the most appropriate follow-up and treatment planning (such as lymph node evaluation, referral to medical oncology, surveillance imaging, possible systemic drug therapy and/or clinical trial participation).

How is the test paid for?

The decision to undergo prognostic testing should be fully discussed with your doctor and loved ones. If you decide you want the information the GEP test provides, Castle Biosciences will work on your behalf with Medicare, commercial insurance providers and, in some cases, your physician’s institution to secure payment coverage for DecisionDx-Melanoma. At this point, Castle Biosciences accepts assignment for all insurance. In addition, the Company believes a patient’s ability to pay for the test should not affect the availability of testing, and has put a Patient Assistance Program in place for those who qualify.

Know Your Risk


A new genomic test is designed to predict if your cancer is at high risk of spreading, based on your tumor’s biology. Watch Video
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Decide with your doctor if DecisionDx-Melanoma is right for you. Download PDF
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