Mammostrat Test


The Mammostrat test, made by Clarient Diagnostic Services, is a genomic test that measures the levels of fivecertain genes in early-stage, hormone-receptor-positive breast cancer cells.

Research suggests the Mammostrat test eventually may be helpful in figuring out if the cancer has a lower or high risk of coming back (recurrence).

Still, all the studies done on the Mammostrat test have been retrospective studies. A retrospective study means the researchers analyzed information that was collected before the study was designed. Many doctors think that the results of retrospective studies aren’t as strong as studies that are designed first and then collect new information specifically for that study (prospective studies).

In the studies on the Mammostrat test, the researchers used the Mammostrat test on samples of breast cancer tissue that had been collected years earlier. The women were part of other studies, so the researchers already knew how many women had had a recurrence. The point of the studies was to see how accurate the Mammostrat test’s predictions were.

While the results were promising, it’s important to remember that until a prospective study is done, Mammostrat test results shouldn’t be used to make treatment decisions. This is why the Mammostrat test isn’t included in the National Comprehensive Cancer Center Network (NCCN) and the American Society of Clinical Oncology (ASCO) treatment guidelines. The NCCN is an alliance of 21 of the world's leading cancer centers. These NCCN centers collaborate on research, guidelines, and education to improve the care of people diagnosed with cancer. ASCO is a national organization of oncologists and other cancer care providers. ASCO guidelines give doctors recommendations for treatments that are supported by much credible research and experience.

In the future, a test that could help figure out whether a woman has a high or low risk of early-stage breast cancer coming back might help women and their doctors decide if chemotherapy or other treatments to reduce risk after surgery are needed.

Who’s eligible for the Mammostrat test?

Mammostrat can be used to analyze early-stage, hormone-receptor-positive breast cancers. Stage I and stage II cancers are early-stage cancers.

The Mammostrat test is performed on preserved tissue that was removed during the original biopsy or surgery.

How does the Mammostrat test work?

The Mammostrat test measures the levels of five genes in breast cancer cells. These measurements are used to calculate a risk index score. Women are assigned to a risk category (high, moderate, or low) based on their risk index score.

If you decide to have the Mammostrat test, you and your doctor will consider a number of factors when deciding whether to add chemotherapy to your treatment plan, including:

  • your age
  • the size of the cancer
  • cancer grade
  • hormone receptor protein levels
  • whether cancer cells were found in nearby lymph nodes

How is the Mammostrat test different from the Oncotype DX test, the MammaPrint test, and the Prosigna assay?

You may have heard about three other tests that analyze breast cancer genes to estimate recurrence risk:

While all four tests analyze genes to help estimate the risk a cancer will come back, there are differences:

  • The Oncotype DX test is used to estimate a woman’s risk of recurrence of early-stage, hormone-receptor-positive breast cancer, as well as how likely she is to benefit from chemotherapy after breast cancer surgery. The Oncotype DX test also is used to estimate a woman’s recurrence risk of DCIS (ductal carcinoma in situ) and/or the risk of a new invasive cancer developing in the same breast, as well as how likely she is to benefit from radiation therapy after DCIS surgery. The Oncotype DX test analyzes the activity of 21 genes and then calculates a recurrence score number between 0 and 100; the higher the score, the greater the risk of recurrence.

    The OncoType DX test is the only one of these four tests that has had prospective study results published. It is also the only one of these four tests that is included in the NCCN and ASCO treatment guidelines. Because of this more rigorous research, the Oncotype DX test is the only one of these tests that can be used to make treatment decisions.
  • Research suggests the MammaPrint test eventually may be used to estimate a woman’s recurrence risk for early-stage breast cancer that is hormone-receptor-positive or hormone-receptor-negative. The MammaPrint test analyzes 70 genes to see how active they are and then calculates either a high-risk or a low-risk recurrence score. Still, the MammaPrint test has only been studied with retrospective research. While the results are promising, more research -- especially prospective studies -- is needed. The MammaPrint test isn’t included in the NCCN and ASCO treatment guidelines, and MammaPrint results shouldn’t be used to make treatment decisions until prospective studies are completed and published.
  • Research suggests the Mammostrat test eventually may be used to estimate a woman’s risk of recurrence of early-stage, hormone-receptor-positive breast cancer. The Mammostrat test measures the levels of five genes in breast cancer cells. These measurements are used to calculate a risk index score. Women are assigned to a risk category (high, moderate, or low) based on their risk index score. Still, the Mammostrat test has only been studied with retrospective research. While the results are promising, more research -- especially prospective studies -- is needed. The Mammostrat test isn’t included in the NCCN and ASCO treatment guidelines, and Mammostrat results shouldn’t be used to make treatment decisions until prospective studies are completed and published.
  • Research suggests the Prosigna assay eventually may be used to estimate the risk of distant recurrence (cancer coming back in a part of the body away from the breast) within 10 years of diagnosis of early-stage hormone-receptor positive disease with up to three positive lymph nodes after 5 years of hormonal therapy treatment in postmenopausal women. The Prosigna assay analyzes the activity of 58 genes and calculates a risk of recurrence score (low, intermediate, or high). Still, the Prosigna test has only been studied with retrospective research. While the results are promising, more research -- especially prospective studies -- is needed. The Prosigna test isn’t included in the NCCN and ASCO treatment guidelines, and Prosigna results shouldn’t be used to make treatment decisions until prospective studies are completed and published.

All four tests can be done on a sample of preserved tissue that was removed from the breast during the original biopsy or surgery.

Insurance coverage for Mammostrat

If you’re considering the Mammostrat test, talk to your insurance company to find out if it’s covered.

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