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Breast Cancer Breast Cancer Basics

How to Spot the Different Types of Breast Cancer

Summary & Participants

Not all breast cancers are the same. Learn about the different tests that can tell you which type of breast cancer you have.

Medically Reviewed On: July 11, 2008

Webcast Transcript

ANNOUNCER: Upon an initial diagnosis, physicians test breast cancer for certain qualities that help them decide on treatment. One of the key things that physicians are interested in is a cancer's HER2 status. Although physicians don't fully understand how the HER2 gene works, it is known that proteins regulated by the HER2 gene help control cell growth and development. However, when there is an overabundance of HER2 proteins on a cancer cell, HER2 can also stimulate the cancer's growth.

MAURA DICKLER, MD: HER2 stands for "human epidermal growth factor receptor type 2," and really it's a name of a receptor that sits on the surface of a breast cancer cell. Everybody has HER2 in their cells, but HER2 is over-expressed in about 20 to 25 percent of women with breast cancer. And HER2 historically, predicts a more aggressive type of breast cancer.

ANNOUNCER: There are two tests physicians use to assess a cancer's HER2 status.

MAURA DICKLER, MD: One looks at protein over-expression on the surface of the breast cancer cell and that test is referred to as an immunohistochemical test or IHC. Immunohistochemistry looks at the staining intensity of the protein on the breast cancer cell surface. The staining intensity can be zero, 1+, 2+, or 3+.

ANNOUNCER: 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 and will more likely respond to anti-HER2 therapy.

MAURA DICKLER, MD: Another test to look for HER2 status is called fluorescence in situ hybridization, or FISH for short. And FISH looks for HER2 gene amplification. It's actually a test that's looking for whether you have too many copies of the HER2 gene in your DNA.

RUTH O'REGAN, MD: The FISH test is actually very specific and, if a breast cancer cell is considered HER2-positive by FISH, that means that it is HER2-positive and it will respond to trastuzumab or Herceptin.

The immunohistochemical antibody test is not as specific, because it relies somewhat on the pathologist's reading of the tumor cell.

ANNOUNCER: HER2 testing is typically done at the time of original biopsy and the results can be reported quickly.

MAURA DICKLER, MD: The HER2 status is typically reported by immunohistochemistry about seven to ten days after initial surgery. The FISH testing or fluorescence in situ hybridization sometimes takes a little longer, but the result typically is back in two weeks.

ANNOUNCER: Establishing a cancer's HER2 status helps physicians develop treatment plans in two ways.

MAURA DICKLER, MD: The results of the HER2 tests are prognostic in that it will actually help us to determine the natural history or the course of that woman's breast cancer. However, HER2 is also predictive of response to therapy and anti-HER2 therapy like Herceptin. And so, therefore, women who are HER2-positive are the ones who are most likely to respond to that treatment. And therapy against HER2 has taken a typically aggressive disease and has made it potentially very treatable.

ANNOUNCER: Herceptin, also known as trastuzumab, is a monoclonal antibody that specifically targets the HER2 protein.

RUTH O'REGAN, MD: A monoclonal antibody is basically a protein that attaches to another protein; in this case, the Herceptin is the protein that basically attaches to the HER2/neu protein on breast cancer cells and in some way inhibits growth of the breast cancer cells.

ANNOUNCER: Although it is unclear how Herceptin actually works, it has been found to be effective in fighting both early-stage and metastatic disease, or cancer that has spread beyond the breast. Herceptin's effectiveness has resulted in HER2 testing becoming standard practice and, in the process, giving hope to people with a previously worse prognosis.

MAURA DICKLER, MD: All women should be tested for HER2 status. It's really important to know if you're positive or if you're negative. We make treatment decisions based on this information. We now have a treatment that can target HER2 and turn off those breast cancer cells and therefore it's important to know if you're positive so that you can be treated with that type of therapy.

RUTH O'REGAN, MD: I usually tell patients with HER2-positive breast cancers that they tend to be more aggressive and that they are associated with a worse prognosis than HER2/neu-negative breast cancers. But, over the past six months or so, we've been able to tell patients that we're hopefully able to turn their poor prognostic breast cancer into actually a good prognostic breast cancer by giving them Herceptin.