Mammostrat Test


The Mammostrat test measures the levels of five genes in breast cancer cells. These genes can affect how the breast cancer will behave and respond to certain treatments. These measurements are used to calculate a risk index score. The higher the risk index score, the more likely the cancer is to come back (recur).

The results of the Mammostrat test, combined with other characteristics of the cancer, may help you and your doctor make a more informed decision about whether or not to have chemotherapy after surgery to treat early-stage, hormone-receptor-positive breast cancer.

Who’s eligible for the Mammostrat test?

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

Most early-stage, hormone-receptor-positive breast cancers that haven’t spread to the lymph nodes are considered to be at low risk for recurrence. After surgery, hormonal therapy, such as an aromatase inhibitor or tamoxifen, is prescribed to reduce the risk that the cancer will come back in the future. Whether or not chemotherapy also is needed has been an area of uncertainty for women and their doctors.

Doctors don’t automatically order the Mammostrat test for every person with breast cancer. If you’ve been diagnosed with early-stage, hormone-receptor-positive breast cancer, the Mammostrat test may help you and your doctor make a more informed decision about whether or not you might benefit from chemotherapy after surgery to remove the breast cancer.

If you have the Mammostrat test, you and your doctor will consider your scores in combination with a number of other 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 does the Mammostrat test work?

The Mammostrat test measures the levels of five genes in breast cancer cells. These genes can affect how the breast cancer will behave and respond to certain treatments. These measurements are used to calculate a risk index score. The higher the risk index, the more likely the cancer is to come back. Women are assigned to a risk category (high, moderate, or low) based on their risk index score:

  • Women in the low risk category have a 7.6% risk of the cancer coming back within 10 years.
  • Women in the moderate risk category have a 16.3% risk of the cancer coming back within 10 years.
  • Women in the high risk category have a 20.9% risk of the cancer coming back within 10 years.

Women in the high risk category are more likely to benefit from chemotherapy in addition to hormonal therapy after surgery. Women in the low risk category may be able to avoid chemotherapy that probably won’t give them any additional benefits.

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

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

While all three tests are somewhat similar, 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 MammaPrint test is used to estimate a women’s recurrence risk for early-stage breast cancer. The breast cancer can be 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. MammaPrint results can help a woman and her doctor make a more informed decision about whether to use chemotherapy to reduce recurrence risk.
  • The Mammostrat test is 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. The higher the risk index, the more likely the cancer is to come back. Women are assigned to a risk category (high, moderate, or low) based on their risk index score.

All three 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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