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Cancer Mythbusters: Breast Cancer Risk

  • Breast cancer is the most common cancer diagnosed in women. One fact we know is that early detection of breast cancer can often make the disease easier to treat, and in some cases, easier to cure. So what are some fast facts that everyone should know about breast cancer risk, and what are some common myths and misconceptions that just aren’t true? In this episode, we’ll tell you what you need to know with the help of two Dana-Farber experts: Brittany Bychkovsky, MD, MSc, and cancer genetic counselor Jill Stopfer, MS, LGC.

    Read the transcript:

    MEGAN: Hi. I'm Megan Riesz, and this is Cancer Mythbusters, a podcast from Dana-Farber Cancer Institute about the many myths and misconceptions in the world of cancer. Every episode, we'll take a look at a myth and debunk it with the help of our world-leading clinicians and researchers.

    Breast cancer is the most common cancer diagnosed in women and, as a result, there’s an almost endless stream of information about the disease on the internet and beyond. One fact we know is that the early detection of breast cancer can oftentimes make the disease easier to treat and, in some cases, easier to cure.

    So, what are some fast facts that everyone should know about breast cancer risk, and what are some common myths and misconceptions that just aren’t true? Today, we’ll tell you what you need to know with the help of two Dana-Farber experts, Dr. Brittany Bychkovsky and, genetic counselor, Jill Stopfer. Welcome both.

    J. STOPFER: Thank you.

    DR. BYCHKOVSKY: Thanks so much.

    MEGAN: So, to start off, Brittany, are there ways that people can reduce breast cancer risk?

    DR. BYCHKOVSKY: So, at a population level, many studies guide us on how to assess an individual’s breast cancer risk. Many factors are modifiable. These are lifestyle factors primarily. However, many factors are not modifiable. This include age, gender, the genes that they inherited from their parents and reproductive factors.

    So, we know that breast cancer risk increases with age. Breast cancer is more common in women than in men. Breast cancer risk is higher if an individual harbors a pathologic or deleterious mutation in a cancer gene such as BRCA1/2, PALB2, CHEK2, ATM, TP53. Breast cancer risk is also influenced by reproductive factors. So, for example, later menopause increases risk, or having more children and breastfeeding decreases risk.

    So, those are the factors that can’t modify, but there are modifiable factors that can affect risk — an individual’s BMI, how much they exercise, their diet, whether they smoke and how much alcohol they consume. So, postmenopausal women with a higher BMI have a higher risk of breast cancer. So, per The Nurses’ Health Study, women who have gained 10 kilos or more since menopause, their risk of breast cancer increases by 18 percent, so if a woman’s lifetime risk is 12 percent, that means if they gained weight after menopause, it increases to 14 percent.

    Exercise meanwhile is associated with a decreased risk of breast cancer; the data shows that the more you exercise, the lower your risk goes. So, I tell my patients to do more now than they’ve been doing before because you can’t do too much.

    So, regarding diet, red meat consumption has been associated with an increased risk of breast cancer and a plant-based diet is associated with a decreased risk. So, the Mediterranean diet has been studied most extensively in the literature and the data shows a diet rich in whole fruits and vegetables is better. Olive oil is great. Nuts decrease risk. There’s actually a Greek island called Ikaria which has the most centenarians, so people over 100 years of age in the world, so they must be doing something right in the Mediterranean.

    Alcohol increases a woman’s risk of breast cancer and actually many other cancers, so now we're recommending no more than four drinks per week for women and approximately six drinks for men. Obviously, these numbers vary depending on what you drink and the alcohol content and what is served or considered as a portion. So, drinking red wine isn’t protective. I get this question all the time and alcohol is alcohol no matter the form. Red wine may have more antioxidants, particularly resveratrol, than other alcoholic drinks, but from a cancer perspective, red wine still increases overall cancer risk and you can get this antioxidant known as resveratrol in your diet from just eating red grapes.

    The other thing that people should avoid is smoking. Smoking increases breast cancer risk, so I strongly encourage all patients to quit smoking, do whatever it takes to quit, and it has been demonstrated that not being able to quit in the past is no predictor of not being able to quit in the future, so, keep trying.

    MEGAN: One of the most common questions that oncologists are asked is whether soy increases your risk of breast cancer. So, what is the deal here?

    DR. BYCHKOVSKY: So, no study has shown that soy increases the risk of breast cancer in humans. So, soy has a bad reputation since it contains phytoestrogens that are similar in structure to estradiol or estrogen. So, if you look at phytoestrogens in isolation in a lab, they seem to increase cancer cell growth, but this hasn’t been showing in people.

    So, in fact, there’s actually data showing that soy food intake, which is rich in isoflavones, which is an antioxidant, that they decrease breast cancer risk, so in Asian women who consume at least 20 milligrams of isoflavones per day, and this may be in the form of soy, but also in other vegetables and foods, their risk of breast cancer is 29 percent lower than women who don’t consume this.

    So, in comparison, Western women typically consume less than 1 milligram of isoflavones per day, so, this doesn’t mean that you should supplement with soy or soy’s protein isolates, which are common additives to protein shakes and bars. Soy protein isolates are not equivalent to soy from wholefood sources, so I tell people there’s just data lacking on soy protein isolates and how that affects cancer risk.

    MEGAN: Another common question is whether there’s a correlation between dairy intake and increased risks. So, is that true?

    DR. BYCHKOVSKY: So, this is an ongoing question and one reason why this is of interest is because breast cancer risk is much lower among Asian women in Asia compared to Asian women in the United States. Dairy may not be the answer for this, because there’s other dietary differences, including soy. There’s also a lot of interest in maybe cruciferous vegetables that includes broccoli, cauliflower and Brussel sprouts, and the thinking is maybe that Asian diet in Asia is richer in cruciferous vegetables and that they may be a little bit more protective. So, I think the information out there that we have on dairy is quite limited.

    Fermented dairy is definitely healthy, because you get probiotics with it, and that includes cheeses, yogurts, and then I also tell people if you can eat organic, head in that direction.

    MEGAN: So, Jill, what is the relationship between family history and breast cancer? And is it true that you're likely to develop breast cancer if there is that family history there?

    J. STOPFER: Right. So, we know that some families have what I call more than their fair share of breast cancer. There’s more breast cancer than you would expect just due to chance alone, but that’s usually the first question we ask ourselves. We take a family history that includes your siblings, your children, your parents and grandparents, and sometimes cousins, and think about the fact that, first of all, breast cancer is pretty common unfortunately.

    So, we will typically see that there, you know, there might be one or a few people with cancer in virtually every family, so that question is sort of our starting place – is there more cancer than we would expect just due to chance alone? And, if there is, then there could be a higher than average risk for breast cancer with that being the clue.

    Now, that said, inherited or genetic risk for cancer comes in different flavors. So, sometimes, there is a single gene that runs from parent to child, parent to child across the generations, and if you’ve inherited that altered gene, you live your life at a much more significantly elevated risk for breast cancer, but that situation is actually fairly uncommon. So, maybe five to seven to 10 percent of breast cancer tops, is due to inheriting a single gene with a more profound effect of that nature. In other families, there may still be genetic influence, but it may be a little more complicated. It may be that there are a variety of genes, each with a little bit of an effect, but additively it can combine to create a risk profile, if you will, maybe due to the effect of 20 or 30 or 40 or more genes all coming together. We're not as good at detecting that sort of genetic risk yet and it’s understandable. It’s more complicated.

    So, the bottom line is your family history does count. It may point to a single gene running from parent to child that we have testing for right now, but even if we can’t find a specific gene as the source of breast cancer risk in the family, we may still assess a person to be at increased risk and to benefit from special guidelines based on our understanding that there are other sorts of genetic risks that we can’t yet detect.

    MEGAN: So, going off that gene conversation, we know that the gene mutations BRCA1 and BRCA2 can increase a woman’s risk of breast and ovarian cancer, so if it turns out that you have inherited these genes, are you definitely going to inherit breast cancer?

    J. STOPFER: So, the BRCA1/BRCA2 BRCA genes are probably best known as the genes that Angelina Jolie had testing for. She brought a remarkable amount of attention to this particular situation and many women fear that if they’re identified with this sort of genetic risk, that it’s just a matter of time, and, honestly, some women even who don’t have an identified gene mutation but have a strong family history think it’s, again, “Just a matter of time. It’s going to happen,” and, honestly, there is no one in that situation who is definitely going to get cancer based on inherited risk.

    What it means to have inherited risk due to a mutation in BRCA1 or BRCA2 is you live your life at substantially higher than average chance, and because of that you will benefit from doing some things differently, and those risks really are considerable, but it is possible to find yourself as an older person in her seventies or eighties having had genetic risk due to BRCA1 or 2 and have never developed a cancer because the odds are not 100 percent and so it’s possible to just get lucky. Nonetheless, we think it’s reasonable, if you know your chances are significantly higher than the average person to really think about doing things differently.

    MEGAN: We’ve done a lot of talking about women with breast cancer, but so do men have to worry about breast cancer at all? And, Brittany, we can start with you.

    DR. BYCHKOVSKY: So, male breast cancer does exist. So, it’s rare. Less than 1 percent of all breast cancers occur in men. When it does occur, we always actually do testing for BRCA1 and 2, because male breast cancer is associated with a BRCA1 and 2 mutation. Male breast cancer, though, is seen in men without these mutations and it can be associated with a variety of conditions including endocrine disorders or other health issues, but it is a situation that I think most men don’t realize that male breast cancer does exist.

    J. STOPFER: Particularly in men who have mutations of the BRCA2 gene, while 1 in 1,000 men in the general population can get male breast cancer, that chance can go as high as over 5 percent in men with BRCA2 gene mutations. And so, just that awareness, I agree, is really important, because when a man might develop a lump on his chest wall, he’s typically not thinking that that’s even a possibility and it’s often explained by being an ingrown hair or it’s a boil or it’s anything but that, and so, this awareness about the fact that men can get breast cancer even though it is rare is very important.

    MEGAN: So, to kind of summarize everything we’ve been talking about, what would you say are the most prominent factors that can increase breast cancer risk and what steps can people take to reduce that risk? And, Jill, if we can start with you there.

    J. STOPFER: So, one of the things that can really very significantly raise your risk for breast cancer risk is your family history, and so knowing your family history is so important, and I think families are increasingly coming to understand that talking with others, sharing that information.

    I think in the past it has been more of a private issue and women didn’t want to burden their relatives with information sometimes; they wanted to protect them, but, in fact, that is not the case. If you don’t know, you can’t take the proper steps to do things differently. So, for example, in our women who have BRCA mutations, we may start screening at the age of 25 with an annual breast MRI and that’s not something that 25-year-olds are doing, and you can’t know whether or not you may be a candidate for that type of more intensive screening if you're not aware of your family history because there has been no discussion in the family about this. So, communication is so important and it does allow people to really push the odds in their favor.

    DR. BYCHKOVSKY: I completely agree with that. I think if a family has an experience with cancer, then individuals in that family should come in and have a cancer genetics evaluation and learn about what they can do to reduce their risk of cancer or participate in high risk cancer screening.

    What’s also, I think, most important from both a cancer perspective and an overall health perspective is to live healthy. So, by that I mean don’t smoke. Enjoy alcohol occasionally, not daily. Integrate exercise into your daily and weekly routine and to try to eat healthy with a diet and whole fruits and vegetables.

    MEGAN: Perfect. Well, thanks so much for being here today and for sharing this helpful information.

    J. STOPFER: Thank you.

    DR. BYCHKOVSKY: Thank you.

    See all Cancer Mythbusters episodes

  • Cancer Genetics
  • Breast Cancer
  • Risk & Prevention