Breast Cancer: What to Know About Genetic Testing with Dr. Meghna Trivedi

Angelique: Welcome, Dr. Trivedi. It’s so wonderful to speak with you today.

Dr. Trivedi: Thank you so much for the invitation.

Angelique: I thought we could begin by talking just in general about breast cancer. How common is breast cancer today?

Dr. Trivedi: The common stat that we like to present is, you know, one in eight women will develop breast cancer over the course of their lifetime. So it’s a very common, disease. You know, we see all different types of breast cancers from very early stage diagnoses to later stage diagnoses. There are many different subtypes of breast cancer, um, and the management can, can differ a lot depending on the different factors.

Angelique: Can you explain that a little bit more about the differences, the different types, and perhaps what makes breast cancer different from other types of cancer?

Dr. Trivedi: So typically with breast cancer, there are three markers that we look at. The estrogen receptor, progesterone receptor, and another marker called HER2. Um, and then another important component as well is the stage of the breast cancer. Breast cancer is staged from zero, which is the earliest stage, all the way up to stage four, um, and so understanding what the stage of the cancer is, can also help us as we develop our treatment plan.

Angelique: Hmm, but that’s interesting. We hear a lot about the stages of a cancer diagnosis, but if I’m understanding correctly, the markers within also help differentiate the type of cancer. Is that right?

Dr. Trivedi: Yeah. Yeah. It helps us, it can be both predictive and prognostic. It can help us determine what treatments are going to be the best fit for the patient.

Angelique: Mm. Let’s talk a bit about the risk factors. What are some risk factors for breast cancer?

Dr. Trivedi: There are a variety of risk factors. Some are within our control and of course some are outside of our control. So some of the risk factors that we see are age, as we get older, our risk for breast cancer increases. We have family history, having a family history of breast cancer is also a significant risk factor for developing breast cancer.

And then there are more controllable issues, lifestyle issues, uh, alcohol intake and, and other types of lifestyle choices that we make, you know, affect our risk for breast cancer. And then there are reproductive factors, how old were you when you had your first period? How old were you when you went into menopause? How many pregnancies did you have? How old were you with your first delivery? All of these are risk factors that we look at. In general, having an earlier onset of your period or first period, uh, or a later onset of your last period, those are risk factors that increase the risk of developing breast cancer. Having no pregnancies or not delivering any children is also a risk factor for developing breast cancer. Having children after the age of 30 is a risk factor for developing breast cancer. So you know, there are, again, a lot of models that are out there that can help us estimate what someone’s five year, 10 year, or even lifetime risk is of developing breast cancer.

Angelique: Well, we talked about the risk factors for breast cancer, but are they the same for all types of cancer, or are these what we discuss specific to breast cancer?

Dr. Trivedi: That’s a great question. Um, I think some of these lifestyle factors increase the risk of multiple different types of cancers. You know, one of the things with breast cancer is that some of these are hormonally driven, and so that’s why these, these reproductive factors, play a role. So I think that, again, is important for breast cancer risk, um, and may not impact risk of other types of cancers, but there, there are some differences,

Angelique: Well, you mentioned also heredity, so would love to discuss that a little bit and wondered if you’re able to say a percentage of breast cancer cases that do stem from a hereditary cause.

Dr. Trivedi: Yeah. So about 5 to 10 percent of breast cancers are due to hereditary cause. Um, so, not super common, but also, a pretty significant amount. So it does have important implications, not just for breast cancer risk and if a diagnosis of breast cancer develops, breast cancer treatment and management, um, but may also impact the risk of other types of cancers. So, so for example, BRCA1 and BRCA2, while they’re both associated with an increased risk of developing breast cancer, we also see an increased risk in ovarian cancer. There’s, an increased risk in pancreatic cancer for men, also an increased risk in prostate cancer. So it encompasses a lot of, uh, different types of, of cancers.

Angelique: Well, I do want to speak about the genetic factors that might put someone more at risk, but you mentioned BRCA genes. So can you explain what the BRCA gene is?

Dr. Trivedi: Quite simply, these are genes that help with DNA, uh, damage repair. And so when there is an error in one of these genes, you know, it can impact the body’s ability to, to repair the DNA. And that’s what increases the risk of breast cancer. Everyone carries these genes. It’s having, uh, what we call a pathogenic variant, so meaning a problematic change in, in the gene, is what, where the, the issue becomes.

Angelique: Hmm. So in, in terms of being positive or negative, when you hear you are positive for the BRCA gene, it typically means that there might be a mutation present.

Dr. Trivedi: Correct. Yeah. So when, you know, you commonly hear I’m BRCA1 or BRCA1 positive, it’s a way of someone communicating generally that they carry an abnormality in this gene that, um, leads to an increased risk of developing cancer.

Angelique: I wonder if there are other genetic factors outside of the BRCA genes that might impact potential risk for breast cancer. Are there other genetic factors?

Dr. Trivedi: Yeah. Yeah. Again, as we’ve learned more about genetics and are able to have the technology to investigate more, we have found, several other genes that are associated with breast cancer predisposition. These are genes like, PALB2, ATM, you know, a lot of them sound, again, they’re just a bunch of letters that are strung together.

Angelique: Mm hmm. Yes.

Dr. Trivedi: Um, but, uh, but there, there certainly are, uh, additional genes now outside of BRCA1 and BRCA2 that we’re learning that are associated with breast cancer risk. It’s a really important question to ask because, in the past when we were doing genetic testing, sometimes we were only looking for the BRCA1 and BRCA2 genes as a risk factor for developing breast cancer. Um, now we have genetic panels that can cover up to 100 different genes that may be associated with a hereditary cancer syndrome, um, and you can have low risk genes, moderate risk genes, and high risk genes and there are some pathogenic variants in genes, which are associated with extremely high risks of developing some sort of cancer, and then there are ones that have lower risk. And so certainly the management is going to be different depending on which, which gene is abnormal. Um, and so there are, guidelines that kind of outline, where does this fall in the risk of developing cancer? And what’s going to be the best way to manage the gene?

I mean, you know, there are some genes that carry such a high risk of developing breast cancer that one could consider doing something called a risk-reducing surgery, like a risk-reducing mastectomy, having the breast tissue prophylactically removed in order to significantly decrease the risk of developing breast cancer.

There are also medications that you can take to try and reduce the risk of developing breast cancer. We call that chemo prevention, but it’s using anti-estrogen therapy in order to try and help reduce the risk of developing breast cancer. So, some people who really have a high risk, again, either due to a genetic predisposition or due to other reasons and risk factors, um, these are important considerations, but they may not be for everyone. It really needs to be individualized.

Angelique: Can you explain a bit more when such measures might be recommended?

Dr. Trivedi: So again, it’s a very personal decision. Um, and so it really depends on the individual. So I think understanding, um, what is your risk of developing breast cancer and what are the benefits to you for having this surgery? Um, you really want to balance those risks and benefits. There are guideline recommendations or considerations, so, for example, you know, with BRCA1 and BRCA2, the risk of developing breast cancer over the course of an individual’s life is, uh, about 60 to 80%. And so that’s a very high risk. And so, uh, for those individuals, it is considered to have a risk reducing prophylactic mastectomy, in order to reduce the risk of developing breast cancer in the future. It’s not mandatory, uh, but it’s certainly something that individuals might consider if, if they want to really effectively reduce the risk of developing breast cancer.

Angelique: So if you wanted to learn more about your genetics and what conditions might be hereditary in your family, how can you go about learning these things? How common is genetic testing? Is it something I can go to my doctor now and say, may I have a genetic test?

Dr. Trivedi: Genetic testing can be done in several different ways. So one way of doing it is, they can take a blood sample. The other way is using a saliva sample. So there are different ways to go about to get the cells in order to sequence them, to extract the DNA. So those are, the two most common ways that DNA can be tested.

I think your primary care doctor is the best place to start. Primary care doctors are often, the kind of the front line, they get family history they have can have a sense of whether or not there’s multiple family members with breast cancer or with any type of cancer, early onset of cancer, um, and so primary care physicians can often refer individuals to meet with genetics counselors, who are specifically trained in talking to individuals, uh, about, what is the family history, draw a full pedigree, which is looking as an outline of multiple different generations in a family and, and who had cancer and what age it was developed at.

Um, I think when you meet with a genetics counselor, they go through your family history in a lot of detail. And I know that can be a challenge sometimes, you may, you know, family can be distant, not everyone is willing to speak about their own health problems, but you know, having as much of your family history that you can know before you meet with a genetics counselor is really helpful, just to make sure that, you know which genes are the most important to test for, um, and then they can return the results to you once you get it back to give you an understanding.

I think now in oncology in general, there’s a lot more implementation of genetic testing, not just to assess risk, but because it has therapeutic or treatment implications as well. So there are many oncologists now that feel comfortable ordering genetic testing and counseling patients on that.

Angelique: So when would you say someone might start taking steps to think about their family history and think about their potential risk factors and maybe screen for different cancers?

Dr. Trivedi: When to implement screening really depends on your risk. And depending on your risk factors and your discussion with your primary care, some people may start earlier. Some people may start later. With breast cancer, uh, specifically again, an average-risk woman can start screening for breast cancer between the age of 40 and 50. With breast cancer screening, there are also lots of different modalities for screening. We have mammogram, we have ultrasound, we have breast MRIs. And so making sure that you’re getting the right type of screening based on your individualized risk is really important.

Angelique: Mm hmm. What are some things we can do on our own in terms of breast health? How can we keep the breast healthy and monitor its health even before a cancer screening might even come to mind?

Dr. Trivedi: Getting a clinical breast exam is really important. You know, [00:14:00] having breast awareness, um, knowing what they feel like, what they look like, so that if something changes, you can bring it to the attention of your clinician. I think those are the most important, uh, things with regards to breast health.

Angelique: Well, thank you so much for helping us really understand this condition much, much better and understand how much we can do proactively to really protect ourselves and our health.

Dr. Trivedi: It’s been my pleasure. Thank you.

Our many thanks to Dr. Trivedi

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