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Understanding HER2-Positive Breast Cancer: Diagnosis, Testing and More
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On behalf of TigerLilly Foundation, CURE spoke with Dr. Angelique Richardson, from UCSD Health, about HER2-positive breast cancer.
Kristie L. Kahl: Can you explain what the HER2 protein is and what it means for a patient's diagnosis?
Dr. Angelique Richardson: Yeah, so HER2 stands for human epidermal growth factor receptor 2. And basically, what that is, is a protein that sits on the breast cancer cell. And when breast cancer cells have too much of it, it tells the breast cancer to grow rapidly and out of control. About one in five or approximately 20% of women diagnosed with breast cancer, will have too much HER2 protein. And the importance of knowing if your breast cancer has HER2 protein expressed on it is because that will determine the types of treatments that we would offer you.
Kristie L. Kahl: Why is testing for HER2 important?
Dr. Angelique Richardson: Because if we find that the HER2 is over expressed or there's too much of it on your breast cancer cells, then we will offer you treatment that will target the HER2 receptor protein.
Kristie L. Kahl: How exactly is HER2-positive breast cancer different from the other subtypes of breast cancer?
Dr. Angelique Richardson: So HER2 breast cancer is more aggressive, it tends to grow faster and spread outside of the breast a lot sooner than the less aggressive, more common hormone-positive and HER- negative breast cancer.
Kristie L. Kahl: Can you discuss the currently available therapies that we have for patients?
Dr. Angelique Richardson: Yes, the good news is that we have a lot of treatments now available for women with HER2-positive breast cancer. One of them, the first one actually that we had to prove was Herceptin (trastuzumab) and that is a monoclonal antibody. And what that is, is a man-made version of our immune system proteins, which are called antibodies. And they're designed to attack a specific target. So, in this case, it's the HER2 protein. We also have drugs like Kadcyla (trastuzumab emtansine), and that's an antibody drug conjugate. So that is a monoclonal antibody as well. But it's linked to a chemotherapy agent. And so that attaches to the HER2 and it gets taken into the cell. And then once it's inside the cell, then it can cause a cell death. And then we also have small molecule or inhibitors or tyrosine kinase inhibitors. And the example of that is lapatinib or [Tukysa (tucatinib)], and that blocks the cell singles from the HER2 protein that tells the cancer to grow. So, we have a fairly good amount of therapy that we have that we can offer.
Kristie L. Kahl: With these therapies that are available now, what is the prognosis for somebody who has HER2-positive breast cancer?
Dr. Angelique Richardson: So now with all of these options, the prognosis for HER2-positive breast cancer is actually quite good. It depends on several factors, of course, including stage of disease, but with these new treatments, we are seeing many women have survival rates that has significantly improved. So both early stage and metastatic breast cancer.
Kristie L. Kahl: What do patients with HER2-positive breast cancer have to look forward to?
Dr. Angelique Richardson: So in the past, having HER2 breast cancer disease was associated with a poor outcome. But we have so many treatment options available now that we didn't have just a few years ago. So I think what they have to look forward to is that there are so many good options available, we really have moved the needle in this area of breast cancer therapy. And there are so many good options that are in the pipeline that we're really excited to see moving to the clinic at some point. So they have to look forward to some other good therapies and perhaps the next best thing is yet to come.
