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Genomic Tests

Updated September 27, 2010

After your initial diagnosis, you may be able to get more tests to help you decide on your treatment options. If you have stage I or stage II breast cancer that is not in the lymph nodes and is hormone receptor-positive, then you may be eligible for a test called a genomic assay.

Genomic assays look at groups of genes in cancer cells and whether they are present, absent or too active, which influences how a cancer is likely to grow and respond to treatment. A cancer with lots of abnormal activity can be treated differently than a cancer with lower levels of abnormal activity.

Two genomic assays are in use:

  • Oncotype DX uses a tumor tissue sample to look at activity patterns in 21 genes, then scores the likelihood of recurrence (the cancer coming back) within ten years. It also predicts whether you are likely to benefit from common chemotherapy regimens. Oncotype DX can be done on the tissue sample that was prepared for the pathologist after surgery—right away or weeks later.
  • MammaPrint looks at the activity of 70 genes to predict whether the cancer poses a low or high risk of recurrence at five and ten years. MammaPrint has to be done on fresh tissue taken and specially prepared at the time of surgery.

Oncotype DX and MammaPrint are still relatively new, so ask about them if your treatment team does not mention them.

Genomic or Genetic?

Genomic assays are different from genetic tests, which look for mutations (abnormal changes) in certain genes (BRCA1 and BRCA2) passed from your mother or your father to you that increase your cancer risk. While BRCA1/2 testing is only for women whose breast cancer may be family-related, Oncotype and MammaPrint are not. Genomic assays look for abnormalities in the genetic makeup of the tumor itself, not in the genes you were born with.

Paying for Tests

Talk to your health insurance carrier to make sure genomic tests are covered. If they are not covered fully or you do not have insurance, ask your treatment team or social worker for information about financial assistance plans. LBBC also has information for you about paying for treatment in our Guide to Understanding Financial Concerns.

Read more about making choices and the people who helped us write this page in LBBC’s Guide to Understanding Treatment Decisions.