Published on October 30, 2020
Metastatic Breast Cancer Treatments
One of the most significant discoveries in recent years is that there is not one single type of breast cancer. Some breast cancers are HER2-positive — HER is a protein that promotes the growth of cancer cells. (HER2-negative describes breast cancer that doesn’t have HER2.) Others are ER-positive, which means the cancer grows in response to estrogen, or PR-positive, it grows in response to progesterone. And some like triple-negative breast cancer don’t have any of these receptors.
It’s important to know your particular type of breast cancer in order to determine the best treatment, said Dr. Marleen Meyers, a medical oncologist at NYU Langone Health. She participated in Patient Power’s “Let’s Talk Metastatic Breast Cancer: What Are My Treatment Options?” program on August 18. The program was the fourth in an eight-part series of webinars on breast cancer airing monthly from May to December.
Treating Breast Cancer
“I think the first thing that I look at is really what we call the biology of the tumor and that basically means how is a breast cancer going to behave based on some of the proteins on the cell surface,” Dr. Meyers said. “So specifically, I would look to see if somebody's estrogen receptor-positive (ER-positive), are they HER2-positive or triple-negative, and that helps guide the type of treatment that I would consider giving somebody.”
Dr. Meyers said she also considers a person’s health status, previous treatment, treatment goals and expectations (shrink the tumor, kill the cancer, etc.) and whether the patient is asymptomatic or has a particular symptom that needs to be addressed such as bone pain that may require radiation.
Breast Cancer Biomarkers
Dr. Natasha Hunter, an oncologist with Seattle Cancer Care Alliance who also participated in the program, echoed the importance of biomarker testing in treatment decisions. She noted that biomarkers fall into two categories: diagnostic (predicting the therapies that the cancer may respond to) and monitoring (is the tumor responding to therapy or becoming resistant?).
She said, for example, if a patient is ER/PR-positive, she would look for the PIK3CA mutation. About 40% of ER/PR positive breast cancers have that mutation, she said. Last year, the FDA approved the targeted therapy PIQRAY, in combination with fulvestrant, for HR-positive, HER2-negative metastatic breast cancer with a PIK3CA mutation.
“I think we will begin to see more and more of these drugs coming down the line — matching mutations with actual therapy — and opening the door to new kinds of treatments,” she said.
Breast Cancer Clinical Trials
Dr. Hunter emphasized the importance of patients joining clinical trials early on, saying there is a misconception that clinical trial participants are “lab rats.”
“And certainly, there have been some terrible things that have happened in the past to destroy trust between physicians and patients, so I think we have to acknowledged that,” she said. “What clinical trials at their best do is combine a standard therapy that we know is effective that's been approved with something that we think is a good idea and compare that against that standard of care.”
Triple-Negative Breast Cancer
For patients with triple-negative breast cancer, treatment is trickier, as most therapies target HER2, progesterone or estrogen.
“You sort of feel you have to try to kill it with chemotherapy,” Dr. Meyers said. “And the problem with that is chemotherapy kills rapidly dividing cells, but we have so many other rapidly dividing cells in our body and the response of triple-negative breast cancer tends to be not so great. So, you end up having a lot of toxicity with a relatively low rate of success in terms of trying to shrink the tumor and alleviate symptoms.”
She noted there are promising immunotherapy treatments, used in combination with chemotherapy, such as atezolizumab (Tecentriq), which the FDA approved for triple-negative breast cancer last year. (Tecentriq had already been approved to treat specific types of urinary and lung cancers.)
Dr. Meyers said she is excited about the surge in FDA drug approvals for breast cancer, largely the HER2 targeted therapies.
“I'm also excited conceptually about a lot of other changes in oncology, largely drugs that are now being formulated in the oral setting,” she said. “So, we can get away from people feeling sick and having to go to an office for their treatment. So, I'm excited about the human aspect of the survivorship in metastatic breast cancer where people, although they are dealing with metastatic breast cancer, they also have a very full wonderful life…”
About the program: “Let’s Talk Metastatic Breast Cancer” was hosted by Dr. Kelly Shanahan, a former obstetrician/gynecologist who was diagnosed with early-stage breast cancer in 2008 and with metastatic disease in 2013. Nunny Reece, who was diagnosed with metastatic breast cancer in 2017 at age 39, helped facilitate the discussion. Reece is on the board of the Tigerlily Foundation.
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