Nadine M. Tung, M.D.: Hello, and welcome to this CURE Expert Connections® program on BRCA-mutated breast cancer. I’m Dr. Nadine Tung from Beth Israel Lahey Health, and I’m joined by Kristin Fleischmann-Rose, also from Beth Israel Lahey. She’s a nurse practitioner, and she’s going to help me shed some light on the use of PARP [poly ADP ribose polymerase] inhibitors in appropriate patients with breast cancer. I thought we would start by discussing the different groups of breast cancer and how we think about classifying breast cancer.
The first group are those who have what we call HER2 [human epidermal growth factor receptor 2]-positive breast cancer. And among those who are HER2-negative, we divide disease between the breast cancers that have a receptor for the female hormones, estrogen or progesterone — so those are the estrogen receptor-positive HER2-negative breast cancers — and those that do not have a receptor for HER2, estrogen, or progesterone. And we call that triple-negative breast cancer.
With regard to the prognosis of those three groups of breast cancers, HER2-positive breast cancer used to be thought of as having the worst prognosis. However, now with HER2-targeted therapies, patients with HER2-positive breast cancer actually do as well as or better than patients who have the other types of breast cancer. I would say that triple-negative breast cancer still has the reputation of being a very aggressive type of breast cancer, and in certain instances that’s true, although there are many patients with triple-negative disease who do very well. And I would say that the estrogen receptor-positive, HER2-negative breast cancers have the characteristic that unlike the other types of breast cancer, they can recur very late: five, 10, or even 15 or more years after diagnosis.
And then finally as a way of introduction, I would say that we’re asked a lot, what are the causes of breast cancer? What are the risk factors? First, I would say that age is probably the No. 1 risk factor. Most breast cancers happen in women who are postmenopausal, over the age of 50. I would say another risk factor is a family history of breast cancer, and particularly a family history of younger breast cancer, which is more indicative that there might be a hereditary component. Third would be breast biopsies that are benign but that show changes that indicate a higher chance of developing breast cancer, like a typical hyperplasia or a lobular carcinoma in situ.
Another group of risk factors would be those that indicate a woman’s had a higher estrogen exposure in her lifetime, and those have to do with reproductive factors like when she started menstruating at a young age, has taken hormone replacement therapy or hormonal contraception, or has children at a later age or has never being pregnant. So that’s another risk factor.
I would say that we hear a lot about breast density. Having dense breasts on mammograms slightly increases the risk of breast cancer, as does having been exposed to radiation at a young age when the breast tissue is still developing. But all of those risks we really have no control over, so a lot of women want to know what they can do to lower their risk of breast cancer. And Kristin and I often tell women to try to maintain optimal weight, to exercise on a regular basis, and to try to limit alcohol to three or four times a week rather than every day. So let me ask you now, Kristin, how common is breast cancer?
Kristin E. Fleischmann-Rose, NP: A statistic that we often hear is that one in eight women develop breast cancer in their lifetime, but breast cancer can develop in people of all genders, as we know. In 2018, there were 330,000 women who developed breast cancer, 20 percent of whom were DCIS [ductal carcinoma in situ], which is the noninvasive type of breast cancer.
Nadine M. Tung, M.D.: Can you say one more word about DCIS, that 20 percent? What’s different about that kind of breast cancer?
Kristin E. Fleischmann-Rose, NP: With the noninvasive type of breast cancer, it means that the breast cancer can’t spread outside of the duct or whichever structure it originates in.
Nadine M. Tung, M.D.: I see. And tell us a little bit about the size and nature of your population of breast cancer patients you care for.
Kristin E. Fleischmann-Rose, NP: Our practice is almost entirely breast cancer patients. We see patients in all stages of the disease: patients in active curative treatment, patients receiving palliative treatment, and patients who are being followed for high-risk disease as well.