IRA FLATOW: This is Science Friday. I’m Ira Flatow.

The US Preventive Services Task Force recently updated its guidelines once again for breast-cancer screening. Women and people assigned female at birth should be getting mammograms at age 40 and continue every other year until age 74. The previous guidelines recommended beginning the screening at age 50.

So why have the guidelines changed, and how are these decisions made in the first place? Joining me now to answer these questions is my guest, Dr. Janie Lee, director of breast imaging at the Fred Hutchinson Cancer Center and at the University of Washington School of Medicine in Seattle. Dr. Lee, welcome to Science Friday.

JANIE LEE: Hi. Thanks for having me.

IRA FLATOW: Nice to have you. Let’s start with an overview of the changes to the breast-cancer screening guidelines, please. Why did the task force come to the decision to lower the screening age?

JANIE LEE: The United States Preventive Services Task Force, also known as the USPSTF, has a pretty rigorous process for evaluating evidence to help them update their guidelines, and they do this periodically. As you know, the last guidelines were issued in 2016.

And so in preparation for these new guidelines, they did what they call a systematic review of the literature that has been published, and they also commissioned a decision analysis to help them better understand how to use the evidence that has been published to improve the guidelines.

And so they specifically looked at studies that have been published in the last decade, and those reports indicate two important things. One is that breast cancer diagnoses in women in their 40s have increased substantially in the past decade since the last recommendations were issued. And in addition, there’s note that Black women are increasingly more likely to develop biologically aggressive cancers, which grow faster and spread faster and tend to be diagnosed at more advanced stages compared to women of other race and ethnicity groups, and thus they have a higher rate of breast-cancer deaths.

And so the guidelines were revised to begin starting at age 40 instead of age 50. And hopefully supporting screening earlier will enable more women to be diagnosed earlier before their cancers can present with symptoms and help us prevent deaths from breast cancer.

IRA FLATOW: Interesting. I want to get into those individual facts a little bit later, but I want to know first, what do you make of these guidelines? Is this in line with what you think should be happening?

JANIE LEE: These new guidelines are definitely good news. As you know, there are multiple organizations that issue screening guidelines, and they vary. And particularly, starting age has been variable across the organizations that issue guidelines. And so updating the USPSTF guidelines to start at age 40 better aligns with other guidelines that have recommended starting at age 40, including the American College of Radiology and the National Comprehensive Cancer Network.

IRA FLATOW: People might be thinking, well, then why did they move the screening age back to 50 in 2009? I mean, the 2002 version began screening at 40, right?

JANIE LEE: Well, first of all, if we could back up a little bit, I do want to be very clear that the evidence is strong and clear that mammography saves lives. There are clinical trials called randomized clinical trials that are considered of the highest quality that have established that screening mammography saves lives. Everybody is in agreement about that. The devil, as you say, is in the details. When do you start? How frequently do you screen?

And so the starting age has been a little controversial because different organizations have different perspectives on how to balance the benefits and the harms of screening. And so what we know is the age-specific incidence of breast cancer, which is, How many cases of breast cancer are diagnosed each year among women in different age groups? increases between the 40s and the 50s and the 60s. And so there’s just more cancer to find in women in their 50s and 60s versus women in their 40s.

You want to balance that with the potential harms of screening, the false alarms associated with having a positive screening test, being asked to come back for additional imaging, maybe having a biopsy that turns out not to have cancer. If there’s less cancer to find, there tend to be more false alarms. And so, What is the right age to start screening and to balance those benefits and harms? is determined by each organization when they have those discussions. That is why that new information that breast-cancer diagnoses are increasing substantially in women in their 40s has shifted their perspective of the USPSTF.

IRA FLATOW: Do we have any idea why this is happening. Why are women getting cancers earlier?

JANIE LEE: Look, that is a really complicated question. It has to do with a lot of factors. There’s sort of underlying biology. There’s exposures. It’s not just breast cancer. People are being diagnosed with colon cancer earlier, too. So is there something about our diet? Is there something about our habits? Are we exercising more? Are we exercising less? BMI, which is Body Mass Index, is also increasing. Is that a contributor? There are a lot of really interesting questions and lots of people studying this. So I think the answer is not entirely clear, but it is being studied.

IRA FLATOW: Right. And speaking of that, you mentioned this earlier, and I want to dig into this a bit more. What are the benefits of earlier screening for Black women specifically?

JANIE LEE: Well, it’s because their cancers are more likely to be biologically aggressive that we want to be screening earlier and potentially more frequently. If you have a slower-growing cancer, if you screen every other year, you might have a good chance of catching it. But if you have a faster-growing cancer, you want to be screening more frequently, say every year, to have a good chance of catching it before it presents with other symptoms. If you can catch it earlier before it has spread, say, to the lymph nodes, you have a better chance of curing the cancer and curing the cancer with less-aggressive treatments that are more focused.

IRA FLATOW: Now, I know the task force did not make a screening recommendation in this report based on breast density, but this is an important factor that scientists are looking at, and can you tell me about what we know about breast density and the risk of developing breast cancer?

JANIE LEE: Breast density is one of several important risk factors for developing breast cancer. It’s an interesting one because not only is it a risk factor, it is a factor that influences our ability to use mammography to detect breast cancers. And that is because breast density, which reflects the amount of glandular tissue– which is where your ducts run– and fibrous tissue– which holds everything together in your breast relative to the fatty tissue in your breast– is white on a mammogram, whereas fatty tissue looks gray. And cancers also tend to look white on a mammogram as well, so it can make it a little bit harder to detect.

Now that being said, having breast density doesn’t automatically mean that a woman is at high risk for breast cancer. I think there’s a little bit of confusion there. It’s certainly an important risk factor to consider, but when you think about your individual risk, you want to consider additional factors like family history and not only just family history, yes or no, but family history in terms of first-degree relatives, number of first-degree relatives, age at which they were diagnosed.

IRA FLATOW: So if you have a family history of breast cancer, the guidelines may be a little bit different for you then?

JANIE LEE: Well, the guidelines are focused on women who are at average risk. There are separate guidelines for women who are identified as being high risk of developing breast cancer, and sometimes being high risk is based on carrying a genetic mutation. And so one of the things that we are telling women, if they are wondering what to do if they receive a letter saying you have dense breasts, we are encouraging women to seek breast-cancer risk assessment, which is a dedicated visit with someone who will review all of your breast-cancer risk factors and may use some breast-cancer risk prediction models. And at the end of that consultation, they may refer you for genetic testing for specific mutations. If one of those is identified, there are specific guidelines about how to proceed and what tests might be used for more intensive screening.

IRA FLATOW: Now that the guidelines have moved, the age back from 50 to 40, are health insurance and Medicare and Medicaid, are they going to be able to follow these guidelines and get you covered at an earlier age?

JANIE LEE: There are many organizations that issue breast-cancer screening guidelines. The ones from the USPSTF are especially important because they are linked to insurance coverage by the Affordable Care Act, which is also known as the Obamacare law. This law requires that private insurers cover preventive services that the USPSTF gives a grade of A or B without cost sharing to the patient, and that’s why these new guidelines, which give screening mammography starting at age 40 a grade of B, are so important.

IRA FLATOW: Because the cancers are starting at earlier ages, I’m curious about why they did not increase the screening rate– instead of one every other year, perhaps one per year. What’s the logic there?

JANIE LEE: That has to do with the focus on balancing benefits and harms. When you move from screening every other year to every year, essentially doubling the number of screens that you perform, the false alarms increase faster than the additional cancers that you can detect. For some people, that is worth it, and for others, it may not be.

And so I will say in our clinical practice, what we recommend is screening at least every two years. We want to communicate that screening works when we are able to use it regularly, and so we want people to plan to come back regularly, whether at annual or biennial, which is every other year, intervals because that is most important. But we do think it is very important. We support women who make the choice to come back every year and also women who make the choice to come back every other year because it’s a better way to balance these benefits and harms.

IRA FLATOW: Speaking of the benefits and risks and talking about– you mentioned women in their 40s. Are you saying they are more likely to receive a false positive than older women?

JANIE LEE: They are because the age-specific incidence of cancer is lower in women in their 40s. Can I give you a numerical example of breast-cancer screening?

IRA FLATOW: Sure. Please. We love to deal with the data here.

JANIE LEE: So let’s take a hypothetical cohort of a thousand women, and all of them are receiving screening mammograms. Look into the punch line first. How many women with cancer do you think we will identify?

IRA FLATOW: This is a quiz. This is not good. I’m bad at quizzes. I’ll say I’ll say five.

JANIE LEE: That’s right. That’s exactly right, about five to six. So for every thousand women we screen, we’ll find five to six cancers.

Now, screening mammography is not a definitive test. It does not tell you whether or not you have breast cancer. It tells you whether there’s something there that requires additional evaluation. So of those thousand women who just got mammograms, how many do you think we’re going to ask to come back for additional evaluation?

IRA FLATOW: Let’s say 50. I don’t know.

JANIE LEE: So about a hundred. The recall rate– we call them recalls, asking someone to come back. The recall rate generally runs between 5% and 12%, but let’s say 10% to make it easier. It’s a hundred women that we are asking to come back for additional evaluation. That is time away from work and family and anxiety that they might have breast cancer, not to mention potentially out-of-pocket costs, but these are going to be removed by the new recommendations. So that is good news.

Out of those hundred women who are coming back for additional imaging, what they’ll do is they’ll get special views with the mammogram that focuses on the area of interest. Maybe they’ll have an ultrasound as well during the same visit, and then we’ll come up with a recommendation. Either we’ll say something like, oh, it turns out to be a benign cyst. It meets all of our ultrasound criteria. Nothing to worry about. We’ll see you next year. Or we might say, you know what? It doesn’t meet our criteria for being something benign that we can tell on this noninvasive imaging. We’re going to have to do a biopsy. And that is about 20 to 25 women who we’re going to ask to come back for a biopsy. And so those 20 to 25 women will receive a biopsy. Luckily, we have already established about five to six will have breast cancer. So you can see why this balancing of benefits and harms is so hard.

IRA FLATOW: What’s your advice to listeners who still feel a bit uncertain about this change? Maybe they were recently told by their doctor to wait until 50 to start screening, and now they go to their doctor and say, I heard about these new recommendations, and their doctor hasn’t heard about them or doesn’t agree with them. What do you say to these people? Find a new doctor?

JANIE LEE: Well, I would say talk to your doctor. Have a conversation about what they know, what you know, what the latest information is. And, particularly, because I think so much of this matters about how people feel about balancing benefits and harms, it really matters what that individual woman’s preferences are. And I think that’s what’s most important because we want people to come back regularly.

If people would prefer to come back every other year but feel a little shy about saying that, I don’t want them to come have a single screen and not come back. We want to set it up and support it so that they’ll come back regularly for screening. And so that’s why we want to support whatever screening plan a woman feels comfortable with.

IRA FLATOW: I understand that. One last question because AI is everywhere now, and I’m wondering how AI might be used to read these scans. Is it being used? Will it be used? Could it find more incidents earlier? What’s your take on this?

JANIE LEE: AI is being used. There are commercially available algorithms that are being used to help with breast-cancer detection. Overall, I would say it is a good thing.

I am a dedicated breast subspecialist, which means all I do clinically is look for breast cancer. There are other radiologists who are more general in what they– certainly they’re trained to, and they read imaging scans for all sorts of conditions, all sorts of imaging modalities, and AI may be helpful in helping someone who doesn’t read breast imaging all the time be as accurate as someone who does.

Now that being said, every AI algorithm is developed in specific populations, and we want to make sure that as we roll these out, these algorithms are validated. They’re tested in other populations to make sure they are as accurate in the population that they were trained in.

One specific example that relates to my own research is women who have a history of treated breast cancer. Turns out there are some changes in their breast related to breast-conservation therapy. It’s not yet clear whether those changes might be flagged as a false alarm by an AI algorithm trained in women that don’t have a history of breast cancer. Or if someone has a mastectomy and you have an AI algorithm that is trained using information from two breasts, what does it do with an algorithm that has one breast but doesn’t have the other side to say, oh, is this symmetric? Is this something I can let go? Might there be a higher false-positive rate in that population?

We just don’t know about specific subpopulations within the larger group, and so additional studies are needed. When you have an algorithm that is very good at detecting breast cancer, that is really good news, but we want to make sure that it performs equally across an entire population. So another concern is, how do algorithms perform in different race and ethnicity groups if they are primarily trained in one group? What we want is what we call performance equity. We want the algorithm to be as accurate in specific groups as it is in the population as a whole. So there are a lot of studies that are going on to do just that to help us apply it better.

IRA FLATOW: Well, Dr. Lee, we’ve run out of time. I want to thank you for being quite informative today.

JANIE LEE: Thank you.

IRA FLATOW: Dr. Janie Lee, director of breast imaging at the Fred Hutchinson Cancer Center and the University of Washington School of Medicine in Seattle, Washington.

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