Oncotype DX and MammaPrint

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When a diagnosis of breast cancer is made, there are specific features of the disease that a doctor needs to know.  These features create a specific picture of the breast cancer, which is then used to make a specific treatment plan for the patient.

The features include tumor size, node involvement, tumor grade, estrogen receptor status, progesterone receptor status and HER2-neu status.  Often, this information alone is enough to decide if a woman should have surgery, radiation therapy, endocrine therapy or chemotherapy.

But in some cases, it is not clear if chemotherapy should be offered for breast cancer treatment.  We now realize that some women do not benefit from chemotherapy – their treatment success will be no greater if they receive chemotherapy because their disease is unlikely to recur, or come back.  If those women get chemotherapy, it is possible that the side effects and possible complications would outweigh any benefit of the medications.  Having a way to determine what patients don’t need chemotherapy would be very helpful.

In order to determine which patients would truly benefit from chemotherapy, two tests can be used: Oncotype DX and MammaPrint.  These tests, also called genomic testing, take a closer look at the breast cancer cells and provide more information about the patient’s specific disease. Some of the patient’s cancer cells are sent to the Oncotype DX or MammaPrint lab.  There, the cancer cells’ DNA is evaluated for specific genes that give a more exact image of that particular breast cancer.  The evaluation results may show that a woman is at low, intermediate or high risk for breast cancer recurrence.  This information can be very useful.

Low risk indicates that the chances of breast cancer recurrence are low.  Chemotherapy will probably not make those chances any lower.

Intermediate risk means that the chances of breast cancer recurrence are moderate.  Chemotherapy may or may not lower those chances any further.  Patients with intermediate risk results should have detailed conversations with their breast cancer care team to decide what is best.

High risk means that the chances of breast cancer recurrence are high.  Chemotherapy in these cases is expected to significantly decrease the chance of recurrence and therefore chemotherapy is recommended for these High risk patients.

It is important to remember that not every person with a breast cancer diagnosis requires an Oncotype DX or Mammaprint evaluation.  For many patients, there is enough information from biopsy and surgery to decide what the best treatment plan should be without performing genomic testing.