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Understanding My Diagnosis

Breast Cancer 101

 Diagnostic Test   Genomic Diagnostic Test   Genetic Test

If you are diagnosed with breast cancer, your doctor may order additional tests to better understand your individual cancer and determine a treatment plan that’s right for you.


Diagnostic TestDiagnostic Tests

Hormones are naturally occurring chemicals in the body that stimulate the growth of hormone-sensitive tissues, such as those in the breast. Estrogen and progesterone are hormones that may help breast cancer grow and spread. Hormonal treatments are designed to block or lower the levels of the hormones in your body that stimulate the growth of your breast cancer.

Your doctor will have a pathologist examine your tumor tissue for the presence of hormone receptors, which are sites on the surfaces of cells to which hormones can bind, activating growth. If your cancer is estrogen or progesterone receptor-positive (ER+/PR+), you may be a candidate for hormonal therapy.

The HER2 gene plays an important role in cell growth and development. It directs the production of Human Epidermal growth Receptors in cancer cells. If the cancer cells have more HER2 receptors than normal, the cancer is HER2 positive (HER2+), which means the cells are receiving more messages than they should and causes the cancer to grow and divide more quickly. If the cells have a typical level of HER2 receptors, the cancer is considered HER2 negative (HER2-). The most common methods to test for HER2 are:

  • IHC (ImmunoHistoChemistry): Measures the levels of HER2 protein on the surface of the cancer cells.
  • FISH (Fluorescence In Situ Hybridization): Measures the copies of the HER2 gene within one cancer cell.

Research has shown that patients with HER2+ breast cancer have a more aggressive disease and greater likelihood of having their cancer return or spread (metastasize), compared to patients with HER2- breast cancer. There are currently four drugs approved for patients with HER2+ breast cancer:

These medications are often used in combination with other chemotherapy agents. Talk to your doctor about the most appropriate regimens for you.

When cancer cells spread, they can travel through the lymph system to other parts of the body. Breast cancer cells are sometimes found in underarm lymph nodes due to their proximity to the breast. Your surgeon can determine your lymph node status by performing a lymph node biopsy, such as a sentinel lymph node biopsy or axillary dissection.

The sentinel "guard" node is considered the first node where cancer cells travel if they move from the breast to the lymphatic system. In a sentinel node biopsy, this node is surgically removed and checked for the presence of cancer cells. If no cancer is found, then other lymph nodes are considered cancer free and left alone. If the sentinel node does contain cancer, then the surgeon will remove additional nodes (an axillary dissection) from the armpit. The more lymph nodes with cancer, the more serious the disease.


Genomic Diagnostic TestGenomic Diagnostic Tests

Advancements have been made in personalized medicine that help patients receive the right treatment at the right time. Genomic tests can now look at the biologic "fingerprint" of tumor cells to determine the likelihood of cancer returning, and the chances that specific therapies, such as chemotherapy or hormonal therapy, will be effective. A number of prognostic tests and predictive tests are available.

One such genomic test, the Oncotype DX Breast Cancer Assay, provides the likelihood of a patient’s breast cancer recurring (coming back) over a 10 year period. The test also predicts whether a patient is likely to benefit from adding chemotherapy to hormonal treatment. Oncotype DX can help you and your doctor make a more informed decision about your treatment plan. The Oncotype DX Recurrence Score® provides key information for treatment decision-making that cannot be determined from traditional measures.

Oncotype DX is for patients with early-stage, ER/PR positive, HER2 negative, node negative and node positive (1-3 nodes) breast cancer. It is the only test incorporated in all major breast cancer treatment guidelines including the National Comprehensive Cancer Network (NCCN®), American Society of Clinical Oncology (ASCO®), National Institute for Health and Care Excellence (NICE), St. Gallen, and European Society for Medical Oncology (ESMO).

Oncotype DX has been extensively evaluated in clinical studies involving more than 60,000 breast cancer patients worldwide, including a long-term outcomes study published in The New England Journal of Medicine1 and a chemotherapy benefit study published in the Journal of Clinical Oncology.2

Visit for more information about Oncotype DX.

Learn more about Oncotype DX

There are other diagnostic tests, such as MammaPrint®3 and Prosigna®4 that are indicated for use as a prognostic marker only, along with other clinicopathologic factors.


Genetic TestGenetic Tests

Most inherited cases of breast cancer are associated with two abnormal genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two).

Everyone has BRCA1 and BRCA2 genes. BRCA genes repair cell damage and keep breast cells growing normally. However, when these genes contain abnormalities or mutations and are passed from generation to generation, it causes abnormal function and breast cancer risk increases. Abnormal BRCA1 and BRCA2 genes may account for up to 10% of all breast cancers, or 1 out of every 10 cases.


Breast CancerVisit to learn more about the different types of breast cancer and tests for screening and diagnosis.


1. Prospective Validation of a 21-Gene Expression Assay in Breast Cancer
2. Gene Expression and Benefit of Chemotherapy in Women With Node-Negative, Estrogen Receptor–Positive Breast Cancer
3. MammaPrint® is a trademark of Agendia, Inc.
4. Prosigna® is a trademark of NanoString Technologies, Inc.

Your treatment plan should be specific to your individual cancer and based on your pathology report and other tests

Learn about potential treatment options

Your treatment plan should be specific to your individual cancer and based on your pathology report and other tests

Learn about potential treatment options