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Breast Cancer and Test Results: Is a Positive Really a Negative?

05/08/2015 01:50 pm ET | Updated May 08, 2016

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I recently received the following text: "Hi! My friend just came back with a double negative on her breast cancer [test]. What does that mean?"

When a patient is faced with the shock and worry associated with breast cancer, there are many issues to face and decisions to be made. The last thing she needs is to be confused by the results of diagnostic tests. Sometimes a "positive" or "negative" test result can be confusing because it's not always clear if it is good or bad news. Your doctor might, for example, tell you that a test result is positive, which gives you the false impression that it's a good outcome. Similarly, when a result is negative, it sounds bad when it could in fact be good news. It's important that you fully understand the implications of any test results, but particularly ones in which the results can be ambiguous.

There are basically two types of medical test results:

"Relative" results: These provide information about how the levels of certain substances compare to those that are considered within a healthy range by the medical community. A blood test would fall in this category.

"Positive" or "Negative" results: these types of tests are used for diagnostic purposes and provide information in a "yes" or "no" format. In medical terms, this translates into a "positive" or "negative" result. A "positive" result in a medical test means that the lab found whatever the test was searching for, which may equate to a good or a bad finding. On the other hand, a "negative" result means that the lab did not find what the test was searching for. Similarly, this could be good or bad news.

Let's decode some results of tests associated with breast cancer:

Positive Biopsy: Not good. This means that the biopsy of the suspicious area on a mammogram or ultrasound (and confirmed by a physical exam) is a pre-cancer or cancer.

Double Negative: Not good. This means that the breast cancer tumor cells do not express the gene for the Estrogen or Progesterone Receptors (the two hormones which represent the "double" in the double negative result). Normal breast tissue cells have estrogen and progesterone receptors which stimulate cell growth and function. When cells go awry and become abnormal (i.e. cancerous), they fail to function correctly or to "express" these receptors. A double negative result for hormone receptors mean that the tumor will not respond to hormonal therapy (usually estrogen antagonists of different types).

Triple Negative: Not good. The "triple" in this test result means that the breast cancer cells do not express the gene for Estrogen, Progesterone or Her2/Neu receptors. These are considered the most aggressive form of breast cancer and must be treated with chemotherapy (and are usually quite responsive to it).

BRCA 1 or BRCA 2 Negative: Good. The BRCA gene, when functioning properly, corrects mistakes in cell function that could lead to mutations. In some cells, genes are mutated because of hereditary mistakes in the gene coding--for example, mistakes that could be passed down from your mother or father and his/her family. When someone is BRCA 1 or BRCA 2 negative, this means that they do not carry these specific breast cancer gene mutations. Most people would consider this a favorable outcome, because their cancer is not linked to a genetic transmission due to mistakes in these specific genes. Also, the patient's children would not be at obvious risk of developing breast or ovarian cancer.

Sentinel Node biopsy Negative: Good. Sentinel lymph nodes are the "first stop" lymph nodes where cancerous cells might "drain" from the breast. When a sentinel node biopsy is negative it means that no cancer cells have been found in the lymph node and, therefore, have not traveled beyond the breast.

When it comes to medical test results, don't be afraid to ask questions. Be sure you understand exactly what your test results are telling you so that you can make informed decisions.

Elizabeth Chabner Thompson, MD, MPH, is a radiation oncologist and founder of BFFL Co (Best Friends for Life), which provides a wide range of products for patients undergoing various surgical procedures or cancer treatments. One such product is the Axillapilla® post-surgery pillow featured on the Katie Couric Show. This heart-shaped pillow provides support and stability for a patient recovering from surgery, especially cardiac surgery.