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Rachel Nash Jerusalem Comprehensive
Breast Clinic
Jerusalem
95484, Israel
Ben-Gurion University of the Negev
Beer-shiva 84105,
Israel
Dr. Kopans is to be congratulated for his constant defense of the mammographic screening process. However, we would like to comment on his recent steadfast rejection of sonography in breast cancer screening [1].
We believe that we [2] erred in terming the sonography examination "screening sonography." The sonography examination is an addon study to a screening mammography process that has been shown to be deficient for women at high risk, or with mammographically dense breasts [3, 4]. We did not intend for this study to stand alone as a screening tool. If Kopans thinks that adjunct sonography needs screening verification, then emerging technologies with promising applications in dense breasts such as digital tomographic mammography and laser mammography should be tested as screening tools before being routinely added to the mammographic screening of dense breasts.
In this context, we believe it is preferable if the sonographer has prior knowledge of the mammogram with normal findings. Knowledge of the geographic distribution of the breast tissue on the mammogram is extremely useful in focusing the add-on sonography study. You know where to look and when to concentrate more closely. With ongoing experience of whole-breast sonography, we have found breast size and the extent of dense mammographic tissue to contribute greatly to examiner fatigue. Prolonged scanning can have a hypnotic effect we call "dream scanning."
The sensitivity of a study with blinded interpretation of the sonogram is likely, in our opinion, to underestimate the true contribution of sonography as an adjunct tool. Kopans [5] has recently stated that no proven sonography criteria differentiate benign solid and malignant lesions. We point out that in all reported sonography screening studies, no carcinomas were detected at follow-up in patients assigned to the "probably benign" category (without biopsy). These are compelling data. Criteria clearly exist. They need to be formulated in an endorsed BI-RADS sonography classification [6]. In our dedicated breast centers, strict adherence to these criteria and same-visit adjunct sonography immediately after screening mammography greatly reduce the harms mentioned. On the contrary, most high-risk women are aware of the deficiencies of mammography and are reassured by the add-on breast sonography. Our biopsy rate of 2.5% is comparable with that of mammographic screening programs [2].
We agree that adjunct sonography has its limitations. It is for the multicenter trial to determine whether the benefits outweigh the costs. It makes no sense to prove its efficacy as a stand-alone screening technique.
References
Avon Foundation Comprehensive Breast
Evaluation Center
Wang
Ambulatory Care Center
Boston, MA 02114
I appreciate the questions raised by Strano and Crystal in their letter concerning my article on breast cancer screening using sonography [1]. Their response, however, suggests a misunderstanding of my motives and a lack of understanding of what constitutes a screening study and how you prove that it is efficacious [2]. I have no intention of championing mammographic screening as "my test." I have fairly extensive experience with breast sonography, having used it continuously for breast evaluation since 1978. In fact, we were among the first to understand the importance of multitechnique breast evaluation and the first to name ourselves a "Breast Imaging" Division [3]. I am well aware of the adjunctive uses of tests in breast evaluation [4]. I am also fully aware of the power and value of breast sonography. My intent was not just to point out the fact that mammography is the only test whose efficacy for screening has been shown by properly performed scientific studies, but to explain why such rigorous tests of efficacy are needed. I happen to think that sonography may, some day, be a useful second-level screening test. I also believe that MRI is even more promising. However, I also understand that when people's health is at stake, beliefs are not sufficient and that important issues associated with the introduction of new screening tests need to be addressed. I have long recognized the importance of establishing efficacy before instituting a new test, and others have taught me why scientific validation is so important.
The fact that the authors would like to evaluate breasts with sonography as an adjunct to mammography does not negate the fact that this adjunctive use is still screening. The test is being applied in an effort to search for occult cancer. If the fact that you have obtained a mammogram makes it all right to evaluate the breast with another technique that has no proven efficacy, then why not use a divining rod? Before dismissing this idea as ludicrous, stop and consider the issues. If a test has no efficacy then its use—even as just an adjunct—is not only a waste of resources, but it may, in fact, be detrimental to the patient. As I tried to convey in the article [1], not only will a new test lead to biopsies for what prove to be benign lesions, but the adjunct may find only nonlethal cancers or cancers that cannot be cured. Such findings could actually result in harming the patient. These uncertainties are why scientific evaluations are performed. Is it valid to prescribe a drug that has no proven efficacy in treating a cancer (and may be harmful) simply because you are also using drugs that have been shown to be efficacious? It must be shown that interventions are, at the least, providing more good than harm. The fact that sonography evaluation seems innocuous does not mean that it cannot have negative consequences.
The letter also suggests a failure to understand the importance of scientific validation as opposed to how a test might be used in clinical practice. I never suggested that sonography would be used to screen the breast instead of mammography. What some seem to have difficulty understanding is that the only way to properly evaluate the role of sonography, or any other test, even if, ultimately, it is to be used in conjunction with other tests, is to first evaluate it in a blinded fashion to understand its independent contribution. Once the contribution has been established, then the results can be added to the other tests to see if it has additive value. When we evaluated whole-breast sonography many years ago, this is exactly what we were taught to do, and recognizing the importance of blinding, we conducted our study that way. One radiologist blinded to the mammograms interpreted the sonograms while another radiologist blinded to the sonograms interpreted the mammograms. Our conclusions were recorded, and then we reinterpreted the studies using the other tests and the clinical information. A blinded study takes a little more effort, but it proved that at that time, sonography had no validity for screening [5] despite the fact that it was being proposed as an adjunct to mammography. Certainly the technology has improved dramatically since then, but the basic issues have not changed. A blinded evaluation is the only way to find out the independent contribution of even an adjunctive study. Once again, if one were to evaluate the role of a divining rod in breast cancer detection, it is obvious that the divining rod could find a large number of cancers if the operator had the mammogram and clinical examination as guides. Obviously sonography is likely to have greater efficacy than a divining rod, but until it is evaluated in a blinded fashion, we actually do not have any proof that this is true.
The decades of controversy over mammography screening have not just been about folks who like to debate. I certainly believe that many of the arguments against mammography have been specious, and I have argued vigorously against them. We have prevailed on the basis of the scientific evidence despite accusations from opponents of screening that radiologists were only being emotional [6]. I have always argued from the science. No other legitimate way exists. Those who argue in support of sonography screening (even as an adjunct) have clearly not understood the lessons learned from the mammography debates. "Evidence-based" is not just a slogan. I must admit that I am surprised that in this day and age some physicians still do not understand the basic and critical importance of science. If we do not provide care that is based on science, then we might just as well be selling snake oil.
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  O. Graf, T. H. Helbich, G. Hopf, C. Graf, and E. A. Sickles Probably Benign Breast Masses at US: Is Follow-up an Acceptable Alternative to Biopsy? Radiology, July 1, 2007; 244(1): 87 - 93. [Abstract] [Full Text] [PDF]
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