What is the Role of Genetic Testing in Breast Cancer? from Patient Empowerment Network on Vimeo.
Breast cancer expert Dr. Julie Gralow discusses the role of genetic testing in metastatic breast cancer care, reviewing the impact of inherited–and acquired–genetic mutations on treatment options.
Dr. Julie Gralow is the Jill Bennett Endowed Professor of Breast Medical Oncology at the University of Washington, Fred Hutchinson Cancer Research Center, and the Seattle Cancer Care Alliance. More about this expert here.
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All right. Dr. Gralow, when you meet with patients, what are some of the more common misconceptions that you hear related to diagnosis?
Well, I think people do confuse – especially at an early diagnosis – that the metastases, the travel to the local lymph nodes, is not the same as a metastatic breast cancer, so we spend some time talking about how it’s still curable and not considered a distant metastasis if the lymph nodes are in the armpit or up above the collarbone, and so, that’s something that we spend some time talking about.
This whole term of “metastatic recurrence” – unfortunately, when you start looking online and get your information from Dr. Google, you read right away that it’s no longer curable, and in 2020, yes, that’s true. That’s probably the most specific statement that we can make. We are not going with curative intent, which means we treat for a defined amount of time, and then all the disease goes away, and we stop treatment, and then you go on with your life, and it never comes back. That would be cure.
But, I think it’s really important to point out that much of metastatic breast cancer can be highly treatable, and what we hope to do – and certainly, at least a subset of metastatic breast cancer – we want to convert it more to what we would call a chronic disease, and so, think of it more like hypertension, high blood pressure, or diabetes. These are diseases that we generally don’t cure with treatment, but that we can control with drug therapy, which sometimes has to be adjusted, and if we don’t control it, we can get some bad complications.
So, that’s not all metastatic breast cancer, unfortunately – we can’t convert all of it to something where we can use a therapy for a long time that keeps it in check and where you have a pretty good quality of life – but we’re hoping that more and more, we’re getting targeted therapies and more specific treatments to patients so that we can convert more patients to a more chronic kind of situation.
Many people are confused about genetic testing. They often think that it relates to ancestry or physical traits like hair and eye color. What’s the role of genetic testing in breast cancer?
Well, you can do genetic testing of the patient’s inheritance, which is how most people think of genetic testing, and that’s actually really important and increasingly important in metastatic breast cancer to do your own inheritance. Have you inherited a gene that was associated with how your cancer developed? Because now, we actually have a class of drugs called PARP inhibitors that are approved for tumors that have a BRCA1 or BRCA2 mutation with them. Most of those mutations were inherited, but not all. Sometimes they can develop as well.
So, now, when my patient – if she didn’t previously have genetic testing for an inherited risk for breast cancer either coming from mom or dad’s side of the family, a lot of people do have that up front, especially if they’re younger at diagnosis or they have a lot of family members with breast cancer. If she didn’t have that genetic testing done previously, at the time of the metastatic occurrence, I’m going to recommend that that be done because knowing if the cancer is associated with one of these DNA repair genes – BRCA1, BRCA2, some other genes – we have a new treatment option, which is an oral pill that actually is highly effective if the tumor has a mutation in one of these.
But, we can also – so, that’s genetic testing of the patient’s own DNA, but we can also do what we call genetic testing – or genomic testing, if you will – of the genes of the cancer. What were the changes in the DNA at the gene level that caused a normal breast cell over time to develop into a cancer cell that’s now growing without responding to our body’s checks and balances? So, what were those mutations, deletions, or amplifications in the tumor itself?
So, we’ve got the patient’s genetics, we’ve got the tumor’s genetics, and both of those come into play when we’re making our best treatment recommendations and trying to understand what the right approach is.
How is testing administered?
So, for our inherited testing, those gene changes can be found in every cell in the body, so we can do that from a simple blood test where we just look at the blood cells. We can actually do it with our sputum and with a cheek swab, even. You can get enough of the DNA from the inside of the mouth to do that.
For a tumor’s genetics, we need some of the tumor, so that’s either done with a biopsy into the metastatic site or, as I mentioned before, increasingly, we’re exploring the potential for a liquid biopsy – so, drawing some blood and then trying to find pieces of the tumor that are shed into the blood.