Dr. Madeleine Tilanus-Linthorst is a member of the department of surgery at the Erasmus University Medical Center in the Netherlands. At the 2019 San Antonio Breast Cancer Symposium, she presented research comparing breast cancer screening with MRI versus mammography in women at high risk of the disease because of strong family history. The results found that MRI found cancers earlier, when they were smaller in size and could potentially change screening standards in the Netherlands and other European countries.
Listen to the podcast to hear Dr. Tilanus-Linthorst explain:
- differences in screening recommendations between the United States and the Netherlands
- why it’s important to find cancers earlier
- the risk of more false-positives with MRI screening
Running time: 11:06
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This podcast is made possible by the generous support of Lilly Oncology.
Jamie DePolo: Hello! We’re podcasting live from the 2019 San Antonio Breast Cancer Symposium. I’m Jamie DePolo, senior editor at Breastcancer.org. Our guest for this podcast is Dr. Madeleine Tilanus-Linthorst, and she’s a member of the department of surgery at the Erasmus University Medical Center. At this conference, she presented research comparing breast cancer screening with MRI versus mammography in women with familial risk. So they had a higher risk of breast cancer because they had family risk.
Dr. Tilanus-Linthorst, welcome to the podcast.
Madeleine Tilanus-Linthorst: Thank you.
Jamie DePolo: So I know and we know that the screen recommendations in the Netherlands are different than the screening recommendations in the U.S. So to start, could you talk about the differences there?
Madeleine Tilanus-Linthorst: Yes. Especially for women with lifetime risk for breast cancer of 20% or higher are advised in the U.S. to get screening with MRI, while in Europe they get the advice to be screened with mammography. The difference is there because we don’t know exactly if a tumor has been found by MRI, how much later that would be detected by mammography? Is that a relevant difference or is it totally irrelevant? So we don’t know exactly the quantity. We wanted to quantify that, and we wanted to look at the disadvantages and to balance that. Therefore, we did this randomized study.
Jamie DePolo: And the women in your study, I just want to confirm, they all had a breast cancer risk of at least 20% or higher, and that was due to having other family members who had been diagnosed, is that right?
Madeleine Tilanus-Linthorst: Exactly. It was based only on mother, sisters, grandmother, even an aunt from paternal side, a sister of the father. If you count that, there are tables for that, you can say if you have a mother and a sister who got breast cancer at age 45 and 55, then your risk to get breast cancer is probably more than twice as high as the normal population. Then MRI screening comes into view as one of the possibilities because if you detect cancers earlier then the risk that they may later metastasize is far smaller.
Jamie DePolo: Okay. Thank you. I also want to say, it doesn’t sound like genetic testing was a part of this study. Is that right?
Madeleine Tilanus-Linthorst: About half of the women went to a genetics department but that can have consequences for mortgages, etc. So not every woman wants that. Those women who did not want to have a real genetic test, we just looked at the family history.
Jamie DePolo: Perfect. So then can you summarize the results of your study for us?
Madeleine Tilanus-Linthorst: Yes. There were 1,355 women in the study, 680 in both groups: 680 screened with MRI, 680 screened with mammography. In the group with MRI, they got MRI yearly and clinical breast exam and an additional mammography every other year, while the group with mammography got only yearly mammography and clinical breast exam. In the group with MRI we detected far more cancers, 3 times as many real breast cancers and twice as many pre-stage cancers, which are not really a threat but give a higher risk of getting invasive breast cancer later and therefore are treated usually.
If you look at the earlier detection, MRI detected the cancers far earlier. The median size was 9 millimeters versus 17 millimeters in the mammography group. We think that’s a significant difference. Further, there were far fewer women who got axillary node involvement. We do know that if you have axillary node involvement, that influences your future prognosis. And that was far lower with MRI than in the mammography group.
Jamie DePolo: Just to clarify, sorry to interrupt, the axillary nodes are the lymph nodes under the armpit, correct?
Madeleine Tilanus-Linthorst: Exactly. These two together, the smaller size and fewer lymph nodes, make the prognosis really better for the women who were screened with MRI. However, there were also drawbacks in the MRI group. We had four more false alarms. One-and-a-half times more often that the MRI said we see something, but afterwards if you had really looked up with other investigations whether it was cancer or not, it proved to be benign. So that was a false alarm for the woman, which is very disturbing and also costly because you do extra examinations.
Jamie DePolo: That could possibly lead to a biopsy, too, correct?
Madeleine Tilanus-Linthorst: Exactly. In the MRI group, for every cancer detected, we had to perform four times a biopsy. In the mammography group, for every cancer detected, we had to perform a biopsy one-and-a-half times. However, because we detected more cancers, if we did a biopsy in the MRI group, the women had a chance of one in three that really was cancer. In the mammography group that was slightly higher chance even, but that was not a big difference. But false alarm is something you try not to have of course. It’s very unpleasant for the women.
Jamie DePolo: Right. So overall it sounds like the MRI found the cancers when they were smaller. There were fewer lymph nodes involved. To me, not being a doctor, it sounds like MRI might be more advantageous. But we do have the more false positives. So what should women think about this? What do they do? What do they need to think about?
Madeleine Tilanus-Linthorst: We think it’s balance and if you can discuss it. At the moment, we do think MRI screening is useful for the whole population. If your risk is too low to detect the cancer then you only have the disadvantages and the risk of the false alarm. If your risk is as high as with familial risk, say twice has high as the normal population, then we think screening with MRI can really reduce the risk for later metastasis and mortality, but the women should be warned that they do have a risk with MRI that there will be more false alarm than when they would have been screened with mammography.
Jamie DePolo: I do want to ask you, there was another study that came out earlier this month. I believe it found similar results and it was looking at MRI versus mammography screening, but this time the women had dense breasts, which put them at a higher risk. So how does that compare to your study because you were just looking at familial risk not necessarily density. So how do we kind of put all this together?
Madeleine Tilanus-Linthorst: We did look at density. Our numbers were not large enough to have exact conclusions per density category. This other study looked at women in the general population who had an increased risk because their breasts were very dense, over 75% of their breasts were dense. Then they got offered screening with MRI and it proved that it halved the percentage of interval cancers if they got the MRI. They also had more false positive results with MRI in this group.
We have looked at density, and we first saw that with increasing density both in the MRI group and in the mammography group your risk for a false positive result increases. Therefore, actually in the lower dense groups with lower than 75% of the breast tissue being dense, MRI was actually even more effective. It detected even more smaller cancers and in the following round fewer large tumors, and it had less false alarm than in the highest density category.
So our study can add to it that if your risk is sufficiently high then also at lower density it can be very advantageous for early detection to have MRI screening and it’s at a lower cost than in the highest density category. But the other study has shown that it is effective to screen with MRI if you are in that highest density category with a normal population risk.
Jamie DePolo: I do feel compelled to point out that MRI does cost more than a mammogram. So that is kind of a struggle because if at least in the U.S., I’m not sure how it is in the Netherlands, if somebody wanted an MRI, I believe even if a doctor prescribed, it may not be completely covered by insurance. So there is also that sort of balance that needs to be considered as well.
Madeleine Tilanus-Linthorst: It certainly needs to be considered because MRI is quite expensive. It’s 7 times more expensive thereabout than a mammography both in the Netherlands and in the U.S. In the Netherlands, every medical step that you make in a year you have your own risk over the total year of 400 Euros, thereabout, which is $400. So your first medical consultation up to 400 you have to pay yourself, also if it’s an MRI. But thereafter, the cost for MRI, if you have an indication, is covered by the insurance. However, the insurance will only cover MRI for familial risk if it has been published and if other results confirm our results. Then it will be discussed in the groups that decide about whether it’s cost effective enough. But we expect with our cost effectiveness study that then it will be covered.
So within about 2 years we expect that for familial risk in the Netherlands MRI will be covered. I hope in the U.S. where it’s already indicated for familial risk the insurances will cover more of the cost because at the moment it’s not fully covered by most, only partly. We hope they will increase their coverage if they see that it’s really cost effective and can reduce mortality.
Jamie DePolo: Thank you so much.