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Breast Cancer Screening and Prevention

Are Some Breast Cancers Different than Others?

Summary & Participants

Certain breast cancers mean different things. Learn what tests can determine the type of breast cancer you have, and how this information can affect your treatment.

Medically Reviewed On: July 11, 2008

Webcast Transcript

ANNOUNCER: When a woman is diagnosed with breast cancer, physicians study the cancer's characteristics and try to develop the most effective treatment plan for her specific type of cancer. In addition to hormone receptor status, another classification that doctors establish is the cancer's HER2 status.

RUTH O'REGAN, MD: HER2 stands for human epidermal growth factor. It's a member of a family of growth factor receptors which are on the surface of certain cancer cells. And the HER2 refers to the second growth factor receptor of this family.

ANNOUNCER: HER2 is a naturally occurring protein, controlled by the HER2 gene that helps regulate cell growth and development.

RUTH O'REGAN, MD: We're not really clear what role it plays in a healthy breast cell. We know, in cancer cells, that it appears to make them more aggressive and is associated with poor prognosis.

ANNOUNCER: It has also been observed that when the HER2 gene is over-expressed, or exists at abnormally high levels, it may contribute to the uncontrolled growth of cells, thereby serving as a catalyst for breast cancer.

When a woman is initially diagnosed with breast cancer, tests are performed at the time of the original biopsy to establish a tumor's HER2 status on a scale that ranges from 0 to 3+. A score of 0 or 1+ means the cancer is HER2-negative. A score of 2+ is borderline and usually requires a confirmatory test to establish HER2 status. A score of 3+ indicates the cancer is HER2-positive, indicating it's more aggressive but also more likely to respond to anti-HER2 therapy.

MAURA DICKLER, MD: HER2 positive breast cancer is only a subset of women who have breast cancer. It makes up about 20 to 25 percent of breast cancer. In HER2 positive breast cancer, HER2 appears to be the driver or the activator of growth in that type of breast cancer.

ANNOUNCER: There are two reasons physicians want to determine a tumor's HER2 status early on.

RUTH O'REGAN, MD: The first one is because it gives prognostic information so that patients whose tumors are HER2/neu-positive are usually more aggressive with a slightly worse prognosis. But the main reason for testing for HER2/neu is because of the developments in the monoclonal antibody called Herceptin.

ANNOUNCER: Herceptin, also known as trastuzumab, is a monoclonal antibody that specifically targets the HER2 protein. A therapeutic antibody contains millions of identical copies of a single antibody, all of which attack the same targets, in this case: the HER2 receptor. Herceptin is given by IV infusion and has been found to be a very effective treatment option in women with both early stage HER2-positive breast cancer and metastatic HER2-positive breast cancer, or cancer that has spread beyond the breast.

RUTH O'REGAN, MD: What Herceptin does is it basically binds to the HER2/neu protein on the surface of the breast cancer cell, and somehow, which we don't really understand, it basically works through some pathways in the cell and basically prevents the cancer cell multiplying and eventually the cancer cell dies.

MAURA DICKLER, MD: Herceptin was initially approved by the FDA in 1998 for the treatment of women who had HER2-positive metastatic breast cancer. And it's very effective for women with that type of breast cancer recurrence, and it can cause major shrinkage in about 20 to 30 percent of those tumors, and it can cause disease stabilization in about half of women.

Recently, studies have been presented that have shown that the use of Herceptin earlier in the course of the disease is very effective at reducing the risk of HER2-positive breast cancer from coming back or metastasizing.

ANNOUNCER: The development of Herceptin as an effective treatment option for women with breast cancer has focused physicians on the importance of establishing a cancer's HER2 status. And testing for HER2 has increasingly become standard of care.

RUTH O'REGAN, MD: Pretty much every woman with breast cancer should be tested for HER2, so that really will be regardless of the stage of presentation. If it's positive, then they need to ask their physician about whether they're a candidate for Herceptin or not.

What I typically tell a patient with a HER2/neu-positive breast cancer is that they are more aggressive cancers with a worse prognosis, but that, with the use of Herceptin, we can markedly improve their outcome from this type of breast cancer.