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Testing for Drug Response
Tamoxifen Response
Includes a personalized report, a letter for your doctor, and toll-free support
Price: $300.00
Order TestingPre-test & Post-test Consultation
Our genetic experts can counsel you before and after testing.
Price: $250 per hour
Call to schedule: 1-877-646-0222
Drug Response Test Finder
Over half of all medications are affected by 3 genes that you can test for: CYP 2D6, 2C9 and 2C19. This tool to see which drugs are affected by these genes.
Start the ToolTAMOXIFEN RESPONSE TESTING
FAQs: Tamoxifen Response Testing
1. I took the genetic test for hereditary breast and ovarian cancer already (the BRCA test). Will those test results tell me about tamoxifen, or do I still need to take the tamoxifen 2D6 test?
These are two different genetic tests, which look at different genes that play roles in cancer risk and drug metabolism, respectively. The test you took, often called the BRCA test, tells you about an inherited risk for developing breast and ovarian cancer. The tamoxifen 2D6 test tells you about whether or not tamoxifen will be an effective treatment for preventing breast cancer recurrence.
Genetic testing for hereditary breast and ovarian cancer checks for mutations in the BRCA1 and BRCA2 genes that are known to be associated with breast and ovarian cancer. This test is appropriate for women whose personal and/or family history places them at high risk for these cancers. This test can provide valuable information to help take preventive action, start high-risk screening practices, and provide relatives with additional information about their risk.
The tamoxifen 2D6 test, by contrast, is a drug metabolism test. This test tells whether the breast cancer, drug tamoxifen is likely to be an effective treatment for you. The 2D6 gene is responsible for metabolizing or activating tamoxifen into its most active form, endoxifen. Up to 7-10 percent of women having special variants of the CYP2D6 gene that prevent them from fully metabolizing tamoxifen. As a result, they may not receive full medical benefit from taking tamoxifen. Studies have shown that these "Poor Metabolizers" have an increased risk for breast cancer recurrence.
The tamoxifen 2D6 test is appropriate for postmenopausal women who are taking or considering taking tamoxifen to prevent the recurrence of breast cancer. Knowing their genetic status, these women can work with their physicians to identify whether alternative treatments, such as aromatase inhibitors, may be more effective for them.
2. I am 40 years old, have breast cancer and was just diagnosed with bone metastasis. I was previously on tamoxifen when I was initially diagnosed with breast cancer. Now I take both Zoloda and tamoxifen for the bone metastasis. Is the CYP2D6 test useful for me?
We are very sorry to hear that your breast cancer has metastasized. The tamoxifen 2D6 test, which tells you your 2D6 metabolism status, could help you in two ways:
First, it will tell whether you have been and will continue to receive the full medical benefit from taking tamoxifen. Around 7-10% of Caucasian women are 2D6 Poor Metabolizers, which means they do not receive the full medical benefit from tamoxifen and thus, have an increased risk for breast cancer recurrence. If you know your 2D6 status, you and your doctor can make more informed decisions about whether to include tamoxifen in your current treatment plan.
If test results were to show that you are a 2D6 Poor Metabolizer, you may or may not find this information reassuring; these test results could provide a possible understanding for the cause of your cancer recurrence). Please discuss this with a genetic counselor at DNA Direct and with your doctor prior to taking the 2D6 test. And realize, too, that this test and the research behind it was not available until recently.
Testing for 2D6 can also help you with future medical management. Since more than 20% of all clinically used medications are metabolized by 2D6, knowing your 2D6 status can help you and your doctor with the future selection of medications. For example: Is codeine an effective pain medication for you? Since 2D6 Poor Metabolizers cannot break down codeine into its active form, morphine, codeine isn't an effective medication for them. Click here for a list of medications affected by 2D6.
3. I am currently using raloxifene (brand name: Evista) along with tamoxifen for breast cancer chemoprevention. Is raloxifene metabolized in the same way as tamoxifen (using 2D6)?
Raloxifene is not metabolized by 2D6 or any of the other cytochrome P450 enzymes, thus 2D6 testing is not relevant to your response to Raloxifene. At this time, there is no genetic test that will determine the effectiveness of raloxifene.
Other alternatives to tamoxifen, called aromatase inhibitors, also do not have a genetic test to predict their effectiveness at this time.
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