Imaging women who are high risk for breast cancer
Dr Maxine Jochelson - Memorial Sloan Kettering Cancer Center, New York City, USA
I presented a talk on a strategy for imaging women at increased risk for developing breast cancer. It was primarily for women who have a greater than 20% risk and primarily BRCA mutation carriers but also women who have been exposed to radiation therapy at a young age affecting their chest, women with a strong family history, some women with a personal history. So I start by just discussing various strategies in terms of imaging – the types of imaging that we routinely do for normal people and then the supplemental imaging that we recommend for women who are at higher risk, particularly those women who have dense breasts where you can mask a breast cancer. Then I also looked at the nuances of the types of cancers that women with different risks get and the rapidity of disease developing in different populations because as we look at those differences it also affects the way we use the imaging modalities.
Can you tell us about the supplement imaging?
We start with the basic mammogram. However, in the United States digital or tomosynthesis is actually becoming the routine screening mammogram, we call it a better mammogram. Now, throughout the world that’s not necessarily true. So when we start talking about the supplemental modalities I look at them as being better anatomic modalities. Then another subgroup are women who have vascular imaging, or physiologic imaging, as a different way of doing supplemental imaging. So the anatomic supplemental modalities are still considered tomosynthesis but, as I said, that’s often our baseline and screening ultrasound. Then when you do those studies it demonstrates that you do detect additional cancers – 1.5-2.0 per thousand for tomo and approximately 3.5 per thousand for ultrasound.
However, in these women with the higher risk we find out that even after doing both of those studies we’re still missing about 45% of the cancers. So looking at a better way of looking at the breast is vascular study which primarily has been MRI. MRI uses contrast and the contrast will enhance the new vessels that are developed when there is a cancer and you can sometimes find a cancer before you can actually see a real mass. MRI finds approximately 97% of all cancers.
That has been standard of care in addition to mammography since 2007, the American Cancer Society guidelines.
Another newer technology is called contrast enhanced mammography and that’s newer and we’re just beginning to demonstrate that it too can find 16 cancers per thousand people. MRI is great but it is very expensive, particularly in the US, in Europe it’s actually not. It is something that’s really not available everywhere. For those of us who work in fancy medical centres on either coast, affluent communities, it’s fairly easy but there are places where there is limited or no MRI capability. One option is to do shorter MRIs, they’re called abbreviated MRIs, and that has been demonstrated to be an equally good modality and you can do two or three MRIs in the same time as a full one, in which case you can make it cheaper and you can do more patients.
There are problems with MRI in terms of the gadolinium. There are some data that show that you see gadolinium deposits in the brain in women who have had multiple MRIs. Although it has never been demonstrated to damage the tissue, patients are concerned. So for those reasons one has to look at other possibilities although I still think that MRI is the best way to evaluate women once a year.
Contrast mammo is one tenth the cost. It is something that you can do, you can do hardware and software additions to a regular mammography unit, if it’s a new enough unit, and you can do a larger number of patients. So that offers another option for patients who either can’t have an MRI, who don’t want to have an MRI or don’t have access to it.
The other thing I talked about is that when women have mutations, particularly women with BRCA1, their tumours grow very quick. The recommendation is to image them every six months. One study from Chicago demonstrated that if you did two MRIs a year then you found all the cancers were under a centimetre, node negative and really shows that that’s really the right thing to do. But it is unlikely our insurers are going to pay for it and it is also difficult for our patients, they don’t enjoy the experience. So one of the things I’ve suggested, and the mammogram doesn’t really find a lot of cancers, so contrast mammo is a nice alternative so you can do contrast, six months later MRI, six months later contrast again. Now, if you don’t have contrast we’re still left with doing the mammogram even though we know it’s actually not going to do us a whole lot of good.
Are there any more recent studies that you would like to highlight?
I actually showed a study, the abbreviated MRI study. There has been a big national trial that is about to be published. This is really comparing MRI to tomosynthesis in women with dense breasts but it demonstrated that abbreviated MRI showed 143% more cancers than tomo. There is also a trial that was just published in The New England Journal and, again, these aren’t so much mutation carriers but also just shows how good the technology is in women with extremely dense breasts. In the Netherlands they’ve started a study of over 40,000 women and they’re going to do four sets of imaging, three analyses and the first analysis was just published in The New England Journal. They were looking at cancer detection rate and also interval cancer rate because an interval cancer comes up in between screening and those are usually bad signs that you’re developing a cancer that could cause a more serious disease. What they showed was that in the women who were not offered an MRI in this trial, because it was prospective randomised, they had an interval cancer rate of 5 per thousand, which is pretty well documented. If you offered them an MRI it was 2.5 per thousand. If they actually had the MRI it’s 0.8 per thousand. When they looked at cancer detection rates MRI found twice as many cancers as the mammogram.
Then I also discussed the fact with a contrast mammo we’re beginning what’s called the CMIST trial which is going to compare contrast mammo to tomosynthesis plus screening ultrasound in women who have dense breasts. So both of the newest trials, all the other data were pretty new to begin with.
Is there anything you’d like to add?
I think it’s a really important field. The earlier we find the cancers, we’ve demonstrated with using MRI in mutation carriers that we have improved overall survival. It’s slow and it takes a while to prove that but each piece of data demonstrates that we’re not only improving survival, we’re reducing the morbidity of the cancers these women do get.