Debating Benefits, Risks Of Routine Mammograms

IRA FLATOW, host:

I'm Ira Flatow. This is SCIENCE FRIDAY from NPR News.

Even with recommendations from the American College of Obstetricians and Gynecologists about when first cervical screening should begin, women and their doctors are still talking about the guidelines for mammograms that were issued earlier in the week. And they recommended briefly - getting to them briefly against routine screening of women in their 40's and against the breast self-exam. And since those guidelines were released, we've seen lots of TV shows and news articles telling us stories of many women who say they detected their cancers in their 40's. They said that without screening they would not have survived to their first mammogram at age of 50.

And it seems hard to argue against these stories, but how do these anecdotes weigh against the panel's data? How do you compare the benefits of possibly saving lives against the harm done to other women through false positives and unneeded surgeries? And is it even possible to know that something that looks like cancer would have ended up being a threat to your life? For a lot of women early detection of something that looks like cancer leaves them with two choices: they either take their chances or they take some preventive action, which could mean a regimen of cancer drugs and mastectomies.

Today, we're going to try to take a closer look at routine breast cancer screening and cancer screening in general and help sort through some of the data that you've been hearing through all week along, and perhaps understand a little better the rationale, the thinking behind guidelines like these. And to do that, let me introduce two guests: Dr. David Dershaw is director of breasts imaging at the Memorial Sloan-Kettering Cancer Center here in New York and he joins us in our studios in New York. Welcome back to SCIENCE FRIDAY.

Dr. DAVID DERSHAW: (Director, Breast Imaging, Memorial Sloan-Kettering Cancer Center) Nice to be here.

FLATOW: You're welcome. Karla Kerlikowske is director of Women's Veterans Comprehensive Health Center, that's at the Veterans Affairs Medical Center in San Francisco. She is also a professor of Medicine, Epidemiology, and Biostatistics at the University of California in San Francisco. And she wrote an editorial accompanying those new guidelines. Welcome to SCIENCE FRIDAY, Dr. Kerlikowske.

Dr. KARLA KERLIKOWSKE: (Director, Women Veterans Comprehensive Health Center, Veterans Affairs Medical Center): Thank you very much.

FLATOW: David, let me ask you to - see if we can get some ground - to lay some ground here to understand the statistics. If I'm a woman under 50, what are that odds that I'm going to die from breast cancer?

Dr. DERSHAW: The odds of dying of breast cancer increase with a woman's age.

FLATOW: Mm-hmm.

Dr. DERSHAW: So, as with other cancers - cancer is a disease of aging - so with other cancers the likelihood of dying increases as you get older. The precipitous increase in risk occurs for women in their 40's, which is why screening is used for women in their 40's.

FLATOW: Right.

Dr. DERSHAW: We used to recommend screening starting at 35, decided that that wasn't worthwhile and we have eliminated screening in that age group.

FLATOW: So, is there a number that you could put on for women, let's say in their 40's?

Dr. DERSHAW: It's half of what it is for women in their 50's, to give it a relative worth.

FLATOW: I've seen numbers like three percent. If a woman - any woman in her 40's, the chance of dying of breast cancer is three percent.

Dr. DERSHAW: That would be an acceptable number, maybe a little high.

FLATOW: Let me ask Karla, is that a good number, Karla?

Dr. KERLIKOWSKE: Well, the risk of getting diagnosed with breast cancer for women in her 40's in the next 10 years is 1.5 percent.

FLATOW: Mm-hmm.

Dr. KERLIKOWSKE: So�

FLATOW: I guess I'm asking this - let me just fill you in on why I'm asking this - because I'm now trying to see that if I'm a woman under 50, if I know what those odds of dying from breast cancer are - and if I'm under 50 and I get a mammogram, how are those odds going to change? I mean, if it's three percent when I'm a woman under 50, let's say, how much does it go down to if I get a mammogram, David?

Dr. DERSHAW: Well, that depends upon which set of data you look at.

(Soundbite of laughter)

FLATOW: That's where it gets tricky.

Dr. DERSHAW: And that makes it really very tricky.

FLATOW: Yeah.

Dr. DERSHAW: So, before I answer that question, let me tell you that essentially there are two different sets of studies that one can look at.

FLATOW: Mm-hmm.

Dr. DERSHAW: One is the set of studies which are called prospective randomized trials and those studies began in the 1960s. And those studies take two groups of women that are as close to identical twins as possible and invite one group to get a mammogram and do not invite the other group to get a mammogram. And they compare what happens with death from breast cancer in the women who were invited to get a mammogram to the women who were not invited to get a mammogram. It doesn't mean they got a mammogram. It doesn't mean if they were not invited, they didn't get a mammogram.

FLATOW: Right.

Dr. DERSHAW: It's simply a function of invitation. That's one set of studies. Since those studies were done - and we believe that they adequately demonstrated that mammographic screening is effective - there are now data that are available that demonstrate what actually happens to women if they go and get mammographic screening versus those who don't go and get mammographic screening. In the first set of studies, we have results that show, first of all, the decrease in death rate percentage-wise is comparable for women in their 40's as it is for women 50 and older. And that that decrease in death rate is in about the 20 to 25 percent range. In�

Dr. KERLIKOWSKE: Actually 15 percent for women 40 to 49, according to the new U.S. Preventative Task Force data.

Dr. DERSHAW: According to their data. According to the prospective randomized trials though, I would argue that the data demonstrate a somewhat improved survival rate, but I don't think it's necessary to argue over those numbers. It's not particularly important. If we look at studies comparing women who actually go and get mammograms and the death rates in those women compared to those who don't - we have a study from Sweden - from Malmo, Sweden, which shows a 45 percent decrease in the likelihood of dying of breast cancer if you actually got mammography compared to women who did not.

There is another study, which I think is very interesting, which was presented at the American Society of Clinical Oncology this year and it came out of Boston. And it looked at 7,000 women who got breast cancer in the 1990s - from 1990 to 1990 - 1999 - and comparing women who got at least two screening mammograms to those who got no mammogram or one mammogram. The women who were screened had a death rate at an average of 12 years of follow up of 5 percent from breast cancer. The women who were not screened had a death rate of 75 percent from breast cancer, which is exactly the same as it was in the general population before the era of mammographic screening.

FLATOW: Mm-hmm.

Dr. DERSHAW: So there are a lot of numbers there, and I think it gets really confusing to look at it, but I think there is really very little doubt that your likelihood of dying of breast cancer, if you get screened, plummets.

FLATOW: Let me just ask Dr. Kerlikowske to respond.

Dr. KERLIKOWSKE: I think anyone can pick an isolated study to support their argument and I think that the point of the U.S. Preventative Task Force was to look at all the data in a very balanced way. They looked at both the randomized controlled trials of screen mammography and they also looked at data that is actually collected in the United States, which is the most up-to-date data, by the Breast Cancer Surveillance Consortium and SEER data that's available.

And so I think if you look at the body of evidence and not just isolated studies, then you can see that, yes, there is a benefit to screening women in their 40s, but that benefit is small, and the issue, when you're going to recommend screening to healthy people - I'm a primary care physician. When a woman walks into my office and she's a healthy person, I have to say, if I'm going to recommend something to her, do the benefits of recommending that outweigh the harms?

And I think that basically what the U.S. Preventive Task Force found, by looking not only at randomized control trial data but data collected in women across the United States, is that the benefit for screening women 40 to 49 is small, and there are harms. So in those situations you basically - it's a toss-up. It's the benefits and the harms. It's not clear that the benefits outweigh the harms.

It is true, as women get older, into their 50s and 60s, not only does the benefit go up, but the harms go down. So now the balance is tilted. So you can say for women 50 to 69, and maybe even a little older, that clearly there is some benefit and it seems to outweigh the harms.

FLATOW: What kind of harm, what kind of harm - Doctor, what kind of harms - we're talking just about, oh, stress, I'm going to be living with this, or what kind of harms are we talking about?

Dr. KERLIKOWSKE: I think we're talking about all the false positives and biopsies that result from mammography, which are higher in younger women because the prevalence of disease is low. And basically the U.S. Preventive Task Force showed that if you have - you have to screen 1,900 women 40 to 49 for 10 years, that's 19,000 mammograms, to avert one death from breast cancer. And in addition to that, you generate 2,000 false positives and all the biopsies that you need to do to prove that someone does not have cancer.

FLATOW: And all the mastectomies that would not have to be done.

Dr. KERLIKOWSKE: Well, and I think that's actually a harder thing to quantify, but clearly we're identifying disease that, in all age groups - it goes up with age, but in all groups - that would not affect someone's survival, and I think really, you know, the key is that we don't - if it's a slow-growing tumor, it doesn't matter whether it's detected on mammography, and we don't do well detecting the fast-growing tumors.

So what you really want to detect are what mammography can't do, is detect those kind of moderately growing tumors, and those will have the greatest impact in potentially changing someone's survival. But that absolute number of tumors is not very large in women in their 40s. It gets a little bit larger in their 50s, and probably the biggest increase is women in their 60s. But I just think that the whole idea of the task force - and they actually said this in 2002 also, this is not that much different of a recommendation - is that when you have the situation where the benefit, it's not clear the benefit of the test outweighs the harms, you need to give women a choice as opposed to just blanketly recommend that everybody get mammography.

And I think in particular, if we can figure out a way to target high-risk women in their 40s, that balance might shift where the benefit is greater than the harms to the population, because right now it's - all we can do is say women in their 40s, you know, average-risk women, this is what happens. What we need to know is in your 40s, if you're high risk and you get screened, what happens? And there are just - there are not data yet to show - there are not data yet to show who that group is.

FLATOW: All right, Dr. Kerlikowske, we have to take a break. We'll come back and do a little more back and forth on this and some calls. Our number, 1-800-989-8255. Also, we're tweeting, twittering @scifri, @-S-C-I-F-R-I, and also on Second Life, look for our SCIENCE FRIDAY island. Stay with us. We'll be right back after this break.

(Soundbite of music)

FLATOW: You're listening to SCIENCE FRIDAY from NPR News. I'm Ira Flatow. We're talking this hour about the new guidelines for breast cancer screening, mammography, with my guest, Karla Kerlikowske, who is director of the Women's Veterans Comprehensive Health Center at the Veterans Affairs Medical Center in San Francisco; David Dershaw, director of breast imaging at Memorial Sloan-Kettering Cancer Center here in New York. Our number, 1-800-989-8255.

What more studying do we need? You know what I noticed, what was interesting is, everybody's concentrating on the low end. They're looking at the 40-year-olds, and I'm looking, I took a look at the recommendations for women over 60, over 70. We don't know anything about the women over 70, and there are, what, 12 million women over 70? I mean, why don't we make recommendations for them? They're living longer. I mean, we just leave them out?

Dr. DERSHAW: Well, no, we don't leave them out. Actually, we have studies that look at women up to 75. When I'm asked - because there are no data, this will just be my point of view. When I'm asked what to do with women who are in that older age range, I tell them that a mammogram catches a breast cancer that would potentially kill a woman in about 10 years. So if you can figure out when you're going to die, if you stop screening 10 years before that, that's a good time.

Now, what that means is that if you have other health issues that are really very life-threatening, that the advantage of mammography is probably minimal in that age group, and in fact, the disadvantages of possibly undergoing biopsies and that sort of thing really have a very negative impact.

It's hard to know when to stop. It's hard to know at what point in life to withdraw the advantage of mammographic screening. And our policy has been if a woman remains desirous of having mammogram done, that means she's taking care of herself, that's a really good thing, and we certainly wouldn't want to deny that to her.

FLATOW: Because if you even look at the data, they're extrapolating the death rates.

Dr. DERSHAW: That's exactly right.

FLATOW: And they're saying that they could be four to five times higher than women in their 40s. Why leave those - look at that, it's a tremendous increase in death rate, and to leave those women, you know, unstudied�

Dr. DERSHAW: Well, we don't withdraw mammography from women. In the United States there is no end point for mammographic screening. So we offer it to the entire population that may have an advantage with it.

FLATOW: Karla Kerlikowske, what about these older women?

Dr. KERLIKOWSKE: I think one of the issues for older women is not even - not necessarily, I mean, somewhat how much, how long they're going to live, but the other question, I think, is what kind of cancer are you going to detect on mammography in that population. So there's the issue of competing risks, the co-morbidities. So at our clinic we - if they have a history of stroke, or they have diabetes, if they have many co-morbidities, then it's unlikely that they'll live long enough that mammography would benefit them, definitely past age 74, maybe even past age 70.

But the other thing that I worry about is the risk of detecting ductal carcinoma in situ, and these slow-growing, invasive cancers that, whether you treat them or not, probably would not impact on their survival, that to me is a big downside to mammography in older women.

All the tumors tend to grow slower as they get older in that population, and so I think if someone is, you know, has no co-morbidities at all and is a really healthy person, then probably screening 70 to 74 is okay, but past age 75 it's really hard to imagine that, you know, that mammography would make a big difference.

What we do in our clinic is we do clinical breast exam. Then we feel we're going to potentially find a significant tumor, that if we did treat it, it would impact their survival.

FLATOW: Let me just - quickly, because I want to get to another topic.

Dr. DERSHAW: Yeah, but doesn't the task force advise against clinical breast examination?

Dr. KERLIKOWSKE: In conjunction with mammography.

Dr. DERSHAW: So it's okay to do it if you don't do a mammogram?

Dr. KERLIKOWSKE: If you don't do a mammogram. So basically for clinical breast exam, they say if you do a mammogram, adding clinical breast exam doesn't add anything, and it really doesn't. It increases the sensitivity of detection of one to two percent.

But a clinical breast exam by itself, they basically say there's insufficient evidence. I actually think there is some indirect evidence in that the Canadian trial of women 50 to 59 compared mammography plus clinical breast exam versus clinical breast exam. So they basically were asking - does mammography add anything? And in that trial, all mammography added was detection of more ductal carcinoma in situ and more small cancers.

So basically in that trial they were saying if you can do a really good clinical breast exam, and you have to be good at it, you have to spend time and, you know, really be good at it, that in these older women, you could potentially find cancers that, if you found them early, it would impact their life.

FLATOW: Let's talk about, in general, women of all ages. The mantra is becoming this week the way to solve is to, like the commercial says, ask your doctor, you know? Are doctors, is your GP, the person you go to under your health-care plan, whatever plan that you have, is that doctor, is your doctor generally able to have the time and the length of discussion to discuss these things with you in the 15 minutes you're going to have in that office about what your options should be?

Dr. DERSHAW: Well, I think that that's an unreasonable expectation. I think that physicians, especially those outside of the specialties that take care of breast cancer, are very confused by these recommendations. The ball is being tossed to people who are not actually responsible for making the decision, and it's being taken away from those who are responsible for making the decision.

It's interesting that the advisory panel did not include anyone who was an authority on breast cancer and no one who was an authority on breast cancer screening. The recommendations were promulgated by people who were number crunchers, who selected studies that would result in the recommendation that they had.

If we're going to have effective screening for any group, for any disease, we have to have simple and easy recommendations to follow. Part of the effectiveness of screening is getting people to come in and be screened, and if we have this large menu of screening options, it becomes extraordinarily confusing, and I think it results in a failure of the screen.

FLATOW: Dr. Kerlikowske?

Dr. KERLIKOWSKE: Well, I am that primary care physician, I can tell you, and I am faced with these challenges all the time, whether it's breast cancer screening or cervical cancer screening or the latest thing for heart disease. And I can tell you that patients want choices. They don't want a one size fits all. They want to know what their risk is and how, whatever that intervention, is going to help them. And I can tell you all the time we use the Internet, we use the Framingham Index, and we figure out someone's cardiac risk. And so I think we are in the mode of doing risk assessment and trying to figure out what's best for that individual and not necessarily one size fits all, and I'm going to do everything for everybody - because patients don't want that.

They see themselves as individuals, and they want to know how these things apply to them.

FLATOW: How many of the average - if we can find an average woman in America - how many women at home with their children, women working, how many women do you think actually heard about this study and actually can take the time to sit down out of their working, busy lives, actually sit and think about this?

Dr. KERLIKOWSKE: I think women, they pay attention to this and they pay attention to the media, and they understand and appreciate things more, I think, than people think. A perfect example of that was when it came out that hormone replacement increases your risk of breast cancer, and the media, there was press releases from the Women's Health Initiative, there was articles in the newspaper. And when women saw that, they responded to it, and prior to the WHI coming out, the amount of hormone replacement in this country was around 50 percent, and I can tell you now, it's around 15 percent.

FLATOW: So is�

Dr. KERLIKOWSKE: So I actually think that women are very good about educating themselves, and they like having the information, and they like being part of the decision.

FLATOW: Is your phone ringing today - these days, since this study came out?

Dr. KERLIKOWSKE: It's been�

(Soundbite of laughter)

Dr. KERLIKOWSKE: It's been ringing all week. They - basically, since last Wednesday, it's been - and - yeah, it's been ringing a lot.

FLATOW: Dr. Dershaw?

Dr. DERSHAW: And I would agree that women have heard about this study, and I think they understand the study. And I think the resultant outrage throughout the country about the recommendations of this panel is based exactly on the fact that women understand this study. They know - either for themselves or for people they know and love - that mammograms have save lives. And they want to have a choice - just as Dr. Kerlikowske said. They want to have a choice, and the panel recommended removing that choice from part of the health care decisions that women get to make. So I think the�

Dr. KERLIKOWSKE: I don't think that's correct, though. I think if you read the guidelines, that is not what it says. And it's not what it said in 2002, either. It said that women should - they should discuss it with their physician and it should be a choice. So I don't think they're saying that women in their 40s should not get mammography. I think they're saying it should not be a routine thing that when someone walks into your office, you give them a requisition and say go get a mammogram.

They're saying you should talk to the person and say there's potential benefits. There's potential harms. I think you are an average-risk woman. You're a high-risk woman. And depending on that, they make the decision, which is very different than saying they shouldn't get it. And I can tell you that I've heard both ways. I've heard people say, well, I'm going to continue to get it. And I think if that's what they choose to do, then that's a good decision for them.

But I've also heard people say, oh, great. I can wait until I'm 50. That's something I just really don't want to do. And I think both of those responses are reasonable. I think they are both reasonable, because women do want those choices. And I just want to make one other comment about the panel. You know, you're saying there wasn't a breast cancer expert on that panel. I mean, the U.S. Preventive Task Force is, you know, a group of scientists that are trained to make informed decisions. They look at all of the data.

And I think one thing that is important that the U.S. Preventive Task Force did is they actually can commission new data analysis and someone to go out and get new data. And I think that - I think they should be commended for the fact that they actually provided new science and information instead of just rehashing the same randomized trial data over and over again.

FLATOW: One quick�

Dr. KERLIKOWSKE: And so, I think, though, I think they've been - I don't think you need - I think in some ways, someone - folks would argue that not having someone, a breast cancer, you know, a radiologist or someone who's expert in this, makes it a more balanced decision.

FLATOW: Okay. I got�

Dr. KERLIKOWSKE: I think there's biases when you have people who, you know, everyone likes their area of expertise.

FLATOW: All right. Dr. Kerlik(ph), I have to give you - one quick rebuttal from David, and that's it.

Dr. KERLIKOWSKE: OK.

Dr. DERSHAW: First, I want to say�

Dr. KERLIKOWSKE: Nice meeting you, David, by the way. I've read a lot of your articles.

(Soundbite of laughter)

Dr. DERSHAW: Thank you. First, I want to say, the panel recommended against routine screening for women in their 40s. That is in black and white. There's absolutely no doubt about it. And that's what the entire issue has been about, firstly. Secondly, there are many experts in analysis of data and in breast cancer screening. And there are many of us who have worked very hard our entire lives to make sure that appropriate women get screened. That's why we stopped screening for women 35 to 39.

FLATOW: Okay.

Dr. DERSHAW: So, there are more experts than just those on the panel.

FLATOW: All right. I have to stop it here. We'll obviously continue with this subject. I want to thank both of you for taking time to be with us. David Dershaw, director of Breast Imaging at Memorial Sloan-Kettering Cancer Center here in New York. Karla Kerlikowske, professor of medicine, epidemiology and biostatistics at UC San Francisco. Thanks for taking time to be with us.

Dr. DERSHAW: Pleasure.

Dr. KERLIKOWSKE: You're welcome. Bye.

FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR News. Transcript provided by NPR, Copyright National Public Radio.