Mammostrat is a breast cancer prognostic test that uses five immunohistochemistry (IHC) stains to stratify estrogen receptor expressing patients into high-, moderate-, and low-risk groups for likelihood of breast cancer recurrence treated with tamoxifen-only. Based upon results presented at recent national medical conferences, postmenopausal patients stratified into the low-risk group have a 7% chance of a distant recurrence over a 10-year period. Patients in the high-risk group have a 22% chance of a distant recurrence over 10 years.
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Which patients should use the Mammostrat test? |
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The Mammostrat test is indicated for postmenopausal women with ER-positive, lymph node-negative breast cancer considering therapies in addition to tamoxifen treatment.
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Can Mammostrat be performed on premenopausal patients? |
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Yes, the test can be performed on ER+ patients of any age who want information about their risk of recurrence, however, the clinical usefulness of the test is clearest in the postmenopausal patient population.
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Can Mammostrat be performed on node-positive patients? |
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Yes, the test can be performed on ER+ patients of any stage who want information about their relative risk of recurrence, however, the clinical usefulness is clearest in node-negative patients.
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What tissue is required for the Mammostrat test? |
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Mammostrat is an immunohistochemistry test performed using tumors preserved in paraffin blocks. Physicians can submit the block for testing or send eight unstained sections of four micrometer thickness.
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Is there a minimum amount of tissue for the test? |
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Each Mammostrat biomarker is assessed by a trained pathologist through direct observation of stained tumor tissue under a microscope. If there are enough tumor cells to determine that the specimen is cancer and to assess estrogen receptor status, there are enough cells to perform Mammostrat testing.
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Can Mammostrat be performed on core or needle biopsy samples? |
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Yes. Because Mammostrat works by the direct visualization of tumor cells, results can be obtained from small tumor samples such as those obtained in a core biopsy. There is no ambiguity whether ‘signal’ is derived from tumor or stromal elements, hyperplastic, in situ, or fibrocystic disease.
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Will insurance reimburse Mammostrat testing? |
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Reimbursement for Mammostrat can be filed using current immunohistochemistry coding and therefore uses routinely-accepted, existing billing practices.
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Where is the Mammostrat test performed? |
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In the US, Mammostrat is currently performed at AmeriPath’s Molecular Profiling Institute, a CLIA-certified esoteric laboratory located in Phoenix, Arizona. AGI is currently identifying potential partners outside the US to improve the availability of the test for patients worldwide.
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What is the turnaround time for a Mammostrat test? |
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The turnaround time for Mammostrat from MPI is seven business days or less once the samples arrive at MPI's laboratory.
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How do I order Mammostrat? |
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In the US, Mammostrat is available exclusively through AmeriPath's Molecular Profiling Institute. Go to How to Order for information about ordering Mammostrat testing from MPI. Currently, oncologists and pathologists outside the US should send samples to MPI. However, AGI is also identifying partners outside the US to increase the availability of the test worldwide. Please contact us for additional information.
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How was Mammostrat developed and validated? |
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Mammostrat was developed by Applied Genomics, Inc. of Huntsville, Alabama. Gene expression data was translated into a large set of antibodies which were tested for their ability to predict breast cancer recurrence in a patient cohort in collaboration with the Clearview Cancer Institute of Huntsville, Alabama. Five antibodies were selected as the best predictors when analyzed together using a mathematical algorithm to combine staining results. This test was first validated using independent institutional cohorts from the British Columbia Cancer Center Agency, the Cleveland Clinic Foundation and the University of Alabama at Birmingham. The development and early validation of the test were published in the Journal of Clinical Oncology in July of 2006.
A definitive clinical trial validation was performed in collaboration with the National Surgical Breast and Bowel Project (NSABP) using archived samples from the B14 and B20 clinical trials of adjuvant therapy for node-negative breast cancer. These clinical trial cohorts were the seminal trials that established tamoxifen and adjuvant chemotherapy as effective therapies and therefore provided an unbiased, independent validation of Mammostrat testing. The Mammostrat NSABP validation results were presented at the San Antonio Breast Cancer Symposium in December of 2006 and American Society of Clinical Oncology annual meeting in June of 2007.
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What are the proteins that are measured in the Mammostrat test? |
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The Mammostrat test measures the presence of five proteins in a breast tumor that are thought to be
associated with
cell cycle regulation (p53 and HTF9C), differentiation (CEACAM5), hypoxia (NDRG1), and nutrient supply (SLC7A5).
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How are the IHC results converted into a risk assessment? |
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The IHC staining for each antibody is measured semi-quantitatively according to specific criteria. The results of this staining are entered into an equation that weights each antibody and provides a “risk index” (equation provided in Ring et al, 2006, Journal of Clinical Oncology). Each risk index is interpreted as low-, moderate-, or high-risk of recurrence based on validated criteria. The Mammostrat report will list the staining result for each antibody, the risk index and category, as well as an interpretation of what the score means for the patient.
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Will the Mammostrat report reveal the result for each antibody? |
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Yes, the Mammostrat report will include a breakdown of the staining result for each antibody in the test, in addition to the overall risk assessment.
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Is Mammostrat FDA approved in the United States? |
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Currently, the test is not FDA approved. However, since the test is performed under strict guidelines in a CLIA-certified laboratory, it can be offered in the US as a home brew assay. Applied Genomics is working to obtain FDA approval.
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