Film-screen mammography in the digital age: A conversation with László Tabár, MD

Applied Radiology recently spoke with noted mammography expert László Tabár, MD on the current state of imaging technology for the detection of breast cancer. Dr. Tabár is a Professor of Radiology at Uppsala School of Medicine, Sweden and the Medical Director of the Department of Mammography, Falun Central Hospital, Falun, Sweden.

Applied Radiology: There has been a lot of talk about the use of digital mammography. How is this new technology affecting the detection of breast cancer?

László Tabár, MD: Although digital mammography is a smart new technology, it still is a “static” method of imaging the breast. This means that it does not, and can not, overcome the basic problem seen with film-screen mammography, which is the difficulty of imaging the dense breast. Digital mammography will be used, however, because of (mostly technical) gadgets and benefits, such as the more user-friendly workstation for the technologist who can see the image immediately, the ability to manipulate the image and adjust enhancement, and easier archiving and transferring of images, etc. In film-screen mammography, if and when a picture is underexposed, you cannot change it; but with digital mammography, the technologists can see and manipulate the image or re-take it immediately.

The goal of any imaging method (film-screen mammography, digital mammography, magnetic resonance [MR], etc.) is to image the basic building blocks of the breast. If there is too much fibrous tissue that impairs our ability to visualize fine details, I don’t see how digital mammography would be significantly better than film-screen mammography.

Digital mammography can never increase sensitivity significantly because it does not solve the problem of imaging dense breasts. With digital, the underlying structures are imaged more or less the same as in film-screen mammography. It is a physical thing: if there are a lot of clouds in the sky, you cannot see through. So, digital mammography is not going to find a significantly larger number of cancers and it will definitely not see a lethal cancer better than film-screen mammography.

AR: So you are saying that in order to have a significant change in sensitivity, we will have to look at imaging from a different point-of-view?

LT: This is where functional imaging methods come in. Those available today are far from perfect and no one dreams of using them as a screening tool. These methods have their limitations, but their potential is much bigger than that of digital mammography.

Functional imaging methods “feel the pulse” of the cancer. These methods will be able to reveal the hot spot, the one that is ready to cause harm, and will also show the extent of it.

One of the big problems today is that surgeons want to cut small, which does not take into account the heterogeneous nature and extent of the disease; therefore, its dogmatic use is incorrect. Women want to have a small amount of tissue removed, which only shows that they are ill-informed about the many variations of tumor types and extent of this disease. The pendulum swung, very unjustifiably, from mastectomy to taking very little tissue. The functional imaging method will sort out where you can take the lump with 1 cm of surrounding tissue and where you must take much more tissue, sometimes the whole breast. So, by using functional imaging methods, not only will the sensitivity increase significantly, but so will our ability to describe the extent of the disease. That will have a significant impact on treatment and recurrence.

AR: What hurdles need to be overcome to make functional imaging feasible as a screening method?

LT: If you only think about MR, which is the best method so far, we need to overcome the poor specificity. With MR, its biggest advantage is also its own enemy: any breast lesion with high metabolism may be shown on MR as a positive finding. Since most of the hyperplastic breast changes (different types of adenosis, lesions associated with apocrine metaplasia, etc.) will show up as “hot spots” on MR, they will account for the large number of false-positive findings.

If I can dream about the future, it would be very good to find a more cancer-specific contrast media that, preferably, could be swallowed and would not have to be injected. Also, the MR unit has to be more organ-specific and more cost effective.

We don’t need to find all the cancers. There are cancers than can easily grow to palpable size and they would never kill the patient. Fortunately, most breast cancers are like that. People don’t know that there are 25 different types of breast cancer, but only a fraction of them are very aggressive from the very beginning and must be caught before the mammogram or digital mammography can see them. Functional imaging will see those hot spots.

The other type of cancer that is of great concern is the cancer that has the propensity for worsening in malignancy grade during its growth. A certain percentage of cancers have this propensity. The primary goal of screening is to prevent breast cancers from growing to advanced stages. The best way to accomplish this goal is to arrest those cancers in their early stages that have the propensity of causing harm later in their natural history.

AR: Do you think there is a need for patient education along these lines?

LT: Absolutely. I am thinking about writing books for women about the complexity of the normal breast, as well as different breast diseases. Women are smart and they can be receptive more quickly than the medical community is.

We have been able to do a good job with screening mammography, but why are we having this conversation? Because we are not satisfied. We are publishing a 45% to 50% decrease in mortality among those who come to screening. That’s brilliant, but if we project it to the United States, 20,000 women would still die. If we were able to catch potentially lethal cancers earlier than we are able to today, then we could reduce mortality further.

AR: How do we get more women to come for screening?

LT: First, education empowers every-body. Knowledge is power. Lack of knowledge increases the feeling of uncertainty.

We have to tell women that if you have 25 different animals in front of you and only have one gun in your hand (mammography), but that gun can kill 85% of those 25 animals; then it is a very good gun. But for the other 15% of the animals, you need another gun (ultrasound), and you may need a third gun (MRI). If we are just making a copy of the same gun, which is basically what digital mammography is, then it will not find more cancers or the more important cancers.

AR: Until then, film-screen mammography will remain the gold standard for breast-cancer detection. What advances have been made in that technology?

LT: We have been striving for two contradictory things: to reduce radiation dose while still providing better image quality. But there are important improvements, such as a better compression plate, and improvements in the film and screen combination, etc.

AR: One of the things you have written about is the use of a radiolucent cushion for mammography.

LT: That’s an ingenious, very simple little device that we tested first on Swedish women.¹ In this study, 66% of the 838 study participants reported that use of the cushion significantly reduced discomfort. The average reduction in pain was 53%. We later tested it in California and we had the same results.² In addition, we have not seen any deterioration of image quality with the use of a pad.

There are both psychological issues and real issues here. The issue is much more complex than just “compression causes pain.” Technologists who are not well trained cause much more pain than the well-trained, specialized technologists. Many times, the breast pain is not coming from the compressed breast, it’s coming from the improperly positioned patient’s compressed pectoral muscle. When the pain lasts 2 or 3 weeks after examination, it’s not the glandular tissue. Glandular tissue causes pain as long as you compress it and for just a few seconds after. If the cassette plate is not angled properly, then you compress the muscle.

When 60% or 70% of women report significantly less pain, then women will be willing to come back. Temporary pain must not keep women away from early detection and all of its benefits.

AR: What is it that is going to truly decrease breast cancer mortality?

LT: We are talking about a worldwide issue, and our goal is to have, preferably, 100% of eligible women come in for screening at regular intervals because screening mammography is one of the most proven diagnostic methods in medicine. It is a great example of evidence-based medicine. Early detection of breast cancer and treatment in early stages is really the key factor for decreasing mortality. It’s surgery plus early detection that accounts for most of the mortality decrease in breast cancer.