Rachel Feltman: According to a recent report by the American Cancer Society, breast cancer diagnoses climbed by 1 percent annually from 2012 to 2021. That increase was sharper in people under the age of 50. With so-called early onset cancers on the rise, scientists are working to sort out the complex tangle of factors that can contribute to someone’s risk.
For Scientific American’s Science Quickly, I’m Rachel Feltman. I’m joined today by Dr. Jasmine McDonald. She is an assistant professor of epidemiology at Columbia University’s Mailman School of Public Health.
Thank you so much for coming in to chat with us today.
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Jasmine McDonald: Thank you for having me.
Feltman: So I know that you study breast cancer, but can you tell me more about your particular area of expertise?
McDonald: I got my training in basic science, and I was very interested in signaling pathways and how those pathways are associated with disease. And now I’m a molecular epidemiologist.
And so I’m very much interested in the progression of developing breast cancer, but how that happens across a woman’s life course, so from in utero to pubertal to postpartum: those periods of time where we know the breast tissue is more sensitive to outside assaults or exposures and how that plays a role in developing breast cancer.
Feltman: Mm, and what has changed about breast cancer risk or, or diagnosis in recent years?
McDonald: There’s been an increase in early onset breast cancer, so this means that there’s an increase in young women developing breast cancer before the age of 50; some even defined it as developing breast cancer before the age of 45.
This is very concerning, as cancer is usually considered a disease of old age. You have to live long enough to develop cancer. But now we’re seeing that this rise in early onset—and it’s not just breast cancer; they’re seeing it in colorectal cancer and some other cancers as well.
But what’s very concerning is that many of the subtypes of breast cancer for young women there’s a high frequency of diagnosis of triple-negative breast cancer or estrogen receptor-negative breast cancer.
And what this means is that the tumor itself is going to be more aggressive. There’s going to be challenges in treating that particular tumor. Outcomes are going to be somewhat worse when you have this particular subtype of breast cancer.
And not only that—if you think about it, these women are quite young. Therefore, even surviving the diagnosis, they have the rest of their life to continue to live with this higher risk of developing a new cancer diagnosis or a recurrent breast cancer diagnosis.
Feltman: And when we look at those rising rates, what are we seeing at the demographic level?
McDonald: So the rising rates are seen pretty much all over. I mean, even—you can see it in Ghana. You can see it in India. Like, it’s really a, a global experience. But we know that Black women, women of African ancestry, are diagnosed at earlier, younger ages. They’re more likely to be diagnosed with the aggressive breast cancer subtypes, like estrogen receptor negative, and they’re more likely to have worse outcomes. And we know that Black women have a greater mortality compared to white women when it comes to being diagnosed with breast cancer—that means dying from the disease.
Feltman: Right. And I definitely wanna talk some more about what might be contributing to that disparity. But before we get into that, what makes it difficult to study cancer risk?
McDonald: Cancer is hard to study because it is a disease of age. You have to live long enough to develop cancer. It’s not something where you are exposed, and then boom, you have the disease, like an infection. This is something where there’s a mutation, that mutation can be harmful or non-harmful, that mutation can cause another mutation, etcetera, etcetera. But it’s a long, latent process. Therefore, when you’re thinking about epidemiology and you’re looking at what causes cancer, oftentimes, what caused the initial mutation or progression may be very distal, or far from the diagnosis.
And so that makes it very challenging, especially—people consider cancer, like, “Oh, like, cancer’s everywhere.” Yes, it is. However, in order to study it, you need a very large population. And that means that when you’re thinking about an exposure—smoking and lung cancer: well, there was a time where there was a very high percentage of people who were smoking, so that was something you could study.
But with breast cancer, there’s so many different causative agents that we consider that you need a very large population to really understand exposures, and that makes it very challenging cost-wise, as well as you need to follow from the time that event happened [to] 20, 30, 40, 50 years in the future.
Feltman: Wow, yeah, so what are you doing in, in your research to try to answer those questions?
McDonald: So we look at intermediate outcomes. One of the things I really am interested in is periods in life where we know the breast tissue is dividing very rapidly. This is in utero, so I’ve looked at women who were exposed to pesticides in the womb and their mammographic density, meaning the density of their breast.
This is when you get a mammogram. And now when you get a mammogram, it tells you if you have dense breasts. We know that breast density is associated with an increased risk of breast cancer. So it’s, like, an intermediate biological marker.
Feltman: Right.
McDonald: I study puberty. We know that an earlier age that a girl starts breast development and the earlier age that she starts her period, the greater the risk for breast cancer. So as an intermediate, you can look at exposures that are associated with an earlier age of developing puberty.
So you start looking at intermediate markers and risk factors that are associated with breast cancer if you can’t follow them for 20, 30, 40, 50 years.
Feltman: Yeah. So what kind of associations are, are you finding?
McDonald: There’s different things I’ve looked at. One is looking at environmental exposure as it relates to pesticides. This is when young kids were running behind the fog trucks ...
Feltman: Right.
McDonald: And it was a pesticide for mosquitoes, but it was used on crops, it was used at the pool, it was used everywhere—where those, I guess, fetus[es] that were exposed in the womb, they have denser breasts. It’s also been shown that they have a higher risk of developing breast cancer if their mother also developed breast cancer.
We also look at personal care product exposure. So we’ve shown that the use of certain hair products, especially, like, hair oils, is associated with an earlier age of starting one’s period, and this was especially in Black girls. And we do see that Black girls develop pubertal markers much earlier than their counterparts. So you can see as young as age five, African American girls developing breast[s], and that is a, a biomarker for developing a high risk factor for breast cancer.
Feltman: You mentioned groups in particular where you, you find the rates of cancer diagnosis really, really concerning. So what do you think is leading to those disparities?
McDonald: So disparities often result from—when there’s something you can do about it, that’s when disparities arise.
Feltman: Mm.
McDonald: So if we think about the incidence rate of breast cancer, typically it’s always been that white women have a higher incidence rate, as in, like, being diagnosed with the disease ...
Feltman: Right.
McDonald: And Black women have a higher mortality rate. Now the rate of being diagnosed with the disease is pretty much equivalent for Black women and white women. And when we think about mortality, the reason that it spread is because of the invention of, like, the mammogram, which allows you to detect it early.
Detecting a tumor early is the best prognostic way to survive from that diagnosis because there’s more that you can do, and you are catching it, hopefully, at an earlier stage, a lower grade, and your outcomes are much better.
But once you put in that technological advancement of mammograms, that has to be equitably available to all populations, regardless of demographic. When that doesn’t occur, disparities exist because there’s one population getting the benefit over the other, so you’ll start seeing those benefits in the statistics of our nation. So when there’s something you can do, disparities will arise.
I think when it also comes to exposures, socially disadvantaged groups have a higher burden of certain structural environmental exposures. And so one thing that we study is the inequity as it comes to beauty standards.
And so when we think about our normal routine as a woman and waking up and doing our hair, putting on lotion—all of those things—spritzing ourselves, it’s not that different. However, we know that Black women, given the nation’s beauty standards—or the societal; it’s not even our nation. I mean, it’s global ...
Feltman: Right.
McDonald: Societal beauty standards. Even in India there’s a high rate of using skin lighteners that contain metals, which are carcinogenic, to achieve lighter skin because lighter skin is more beautiful, it’s more acceptable, it’s more societally advancing.
So in the United States straight hair is more acceptable. I’ve known people who got fired for having cornrows—who worked in the back of a shop ...
Feltman: Wow.
McDonald: Didn’t even see customers and still got fired for wearing cornrows ...
Feltman: Wow, yeah.
McDonald: So that means that there’s been products that are overburdened in a certain population that are not experienced in other populations ...
Feltman: Right.
McDonald: Like perms and relaxers. And perms and relaxers is something that are unique to the Black experience. It’s also something that starts very early in age. It’s also something that’s chronic usage. It’s not a one-hit problem. Once you start using it, you usually have to continue using it—unless you cut off all your hair ...
Feltman: Right.
McDonald: And do the big chop.
So we’re talking about young age of exposure, repetitive exposure cumulatively. And this all plays a role in having an overburden of adverse chemicals like endocrine-disruptor chemicals, carcinogenic chemicals that increases your risk of having cellular mutation. And that cellular mutation being advantageous for tumor progression—or tumor initiation to progression.
Feltman: Yeah. I think a lot of people, when they think about cancer risk and read about cancer risk, they see a lot of, a lot of stuff about lifestyle that can be, you know, really very frustrating and, and unhelpful. What needs to change at the systemic level to address this stuff?
McDonald: Systemically, people can’t be blamed for the environment that they live in.
Feltman: Right.
McDonald: I mean, it’s just not fair. I mean, there’s only so much an individual can do, and sometimes what the individual is doing is overridden by the environment.
Feltman: Right.
McDonald: Like, we know that endocrine-disruptor chemicals have their hormonal agents that can disrupt our natural hormonal system. Our hormones are linked to so many things: It’s bidirectional communication with our immune system. It’s linked to periods, obesity, everything from birth outcomes. Like, it’s so pervasive. But yet we don’t really acknowledge that endocrine-disruptor chemicals are in our food packaging, in our personal care products, if you go into buildings that smell really amazing [laughs]. You know, like ...
Feltman: Yeah.
McDonald: Like, really, they’re just environmentally pervasive. But yet we as an individual are supposed to individually change our lifestyle and behaviors to decrease our breast cancer risk. I think societally there needs to be federal regulations that reduce our exposure to these toxicants because there’s only so much an individual can do, and why do we blame the individual for developing cancer?
Feltman: Right.
McDonald: Cancer is not something—I mean, yes, radiation, okay, but even people, even pilots, who fly all the time, I mean [laughs] ...
Feltman: Yeah.
McDonald: You know, there’s just—there’s something about it where cancer’s one of the—those things where they say, “Well, it’s your fault. Like, you did something. You could have done something to prevent this,” and that’s not truly the case.
I have a friend who, I mean, ridiculously healthy—like, just, like, makes-her-own-granola healthy.
Feltman: Yeah ...
McDonald: And developed breast cancer ...
Feltman: Yeah.
McDonald: At a young age. There was no lifestyle factor that would have contributed to that.
Feltman: Yeah, I think, I think, speaking from personal experience for a few family members who had cancer at a young age, I think a lot of that stuff comes from people’s fear: They wanna feel like they’re in control of their future health. They wanna feel like there’s something that they’re doing that’s gonna prevent that from happening to them. As you said, like, a lot of, a lot of systemic stuff [laughs] is way bigger of an issue.
The personal blame—totally inappropriate, unhelpful—but I think a lot of people listening to this or watching this who maybe aren’t thinking about personal care products, for example, might want to know what they can do to, to avoid these exposures. So what advice do you have for them?
McDonald: So my advice is that, you know, when you’re picking out a product, especially when we’re talking about a personal care product, that’s gonna be absorbed into the largest organ of your body, the skin, or going to be directly absorbed by your scalp or things that are gonna just sit on you, you wanna make sure you’re selecting products that are less toxic.
So for example, when you see a product that says “fragrance,” that is a synonym for phthalates, which are endocrine-disruptor chemicals that have been associated with a number of adverse health outcomes, including preterm birth. If you see parabens, those are endocrine-disruptor chemicals. I also don’t believe that individuals need to get a chemistry degree ...
Feltman: Right.
McDonald: To pick a product. So there are different apps out there where you can scan the product if you’re in person with your phone. If you’re buying a product from, like, Amazon or Walmart, there’s Clearya, where when you select it, it’s a little app that tells you if it’s, like, very harmful or what harmful chemicals are in it.
So there are ways to choose a healthier, less toxic product that’s affordable as well because a lot of people have—the concern is, like, “Oh, there’s no way I can change my behavior because I can’t afford it.” But there are affordable less-toxic products.
And we also have to really consider our children. They don’t have the autonomy on what gets placed on their body or their hair. They’re often using either baby products or toddler products, which also may be quite harmful. Even no-lye relaxer that was made for young Black girls contains chemicals that are banned by the European Union Cosmetic Directive.
Feltman: Wow, yeah.
McDonald: So we also have to be considerate, like, are we using products in our household that are household-friendly for everyone?
I also suggest just changing things over time because it can be very overwhelming to say, like, “Oh, my gosh, like, I have to change my perfume, my lotion, my mascara, my—” It is a lifestyle. It is a habit. It is a routine. And as long as it took you to find that perfect shade of eyeshadow, well, now you have to re…discover a perfect shade of eyeshadow that is less toxic. And have fun with it ...
Feltman: Right.
McDonald: You know? Like, don’t make it such that you’re adding stress ’cause stress is also carcinogenic, so [laughs].
Feltman: [Laughs] That’s a great point.
McDonald: So, you know, have fun with it, but choose that item that you cannot go without.
Feltman: Right.
McDonald: And then change that ...
Feltman: Yeah.
McDonald: And then choose the next item, and then keep going.
Feltman: Right.
McDonald: I also say that, you know, when it comes to plastics, don’t microwave food in plastics. Don’t eat hot food out of plastics. Avoid using plastic spoons and forks when you’re eating hot foods. This may mean that you have to replace one Tupperware for another. This means that you may have to invest in a really nice water bottle over another. But these are long-term investments that have long-term health benefits because you are reducing your exposures.
Feltman: Right. And I love the point you made about going slowly because, you know, I think it can be easy to lose sight of the fact that every little change you make is a good change.
McDonald: Exactly.
Feltman: And it’s often way more sustainable to do it that way than try to clean your house out all at once [laughs] ...
McDonald: Exactly. And the thing is, like, people don’t realize but some of these chemicals have a very short half-life. That means, like, you use ’em; you pee ’em out. You use ’em; you pee ’em out. The only reason they are so harmful is because we use them routinely ...
Feltman: Right.
McDonald: It’s part of our routine. So even though they get metabolized and they’re out of your system very quickly, you do something every day and every day—consistently, chronically, you’re exposing yourself.
And that’s why changing your routine—you know, just saying, like, “Okay, you know what? I have to wear this particular eyeshadow, so let me go to XYZ store to find something that is less toxic, and see how I like it.” And then keep going like that.
Feltman: I’m sure a lot of viewers and listeners will want to check out some of the apps and other resources you mentioned, so we’ll definitely include those in, in our show notes so folks can find them.
McDonald: Yes, and I just want to also say there’s, for your listeners who are of African ancestry, Breast Cancer Prevention Partners has a Non-Toxic Black Beauty Project that highlights different Black-owned companies that are producing clean, nontoxic products. For example, Sienna Naturals is Issa Rae and Hannah Diop’s new line, and I’m only saying that ’cause I use it [laughs] and I do enjoy it.
But there are many, many products. A lot of people feel like, “Okay, especially as a Black woman, like, is it even gonna work? Like, I already have, like, pretty much a store in my house of products that I no longer use …”
Feltman: Yeah.
McDonald: “’Cause they don’t work.”
Feltman: Mm-hmm.
McDonald: Don’t let that deter you from changing your lifestyle. Don’t give up. You didn’t give up when you found the perfect shampoo in the first place, so don’t give up for finding, like, that perfect alternative.
Feltman: Yeah, that’s great advice. Thank you so much for coming on to chat today.
McDonald: Oh, thank you so much. I really appreciate it.
Feltman: That’s all for today’s episode. If you want to hear more of our conversation, you can find an extended version on Scientific American’s YouTube channel—and you’ll get to see our recording studio, which is super cute!
Science Quickly is produced by me, Rachel Feltman, along with Fonda Mwangi, Kelso Harper, Madison Goldberg and Jeff DelViscio. Shayna Posses and Aaron Shattuck fact-check our show. Our theme music was composed by Dominic Smith. Subscribe to Scientific American for more up-to-date and in-depth science news.
For Scientific American, this is Rachel Feltman. See you next time!
