The Role of Breast Self-Examination

So how can a woman prudently and effectively improve her chances of detecting breast cancer? What alternatives and adjuncts are there to annual mammography? What new developments are in the pipeline?

First, the value of a really thorough clinical breast examination (CBE) and breast self-examination (BSE) has been routinely downplayed and underestimated by the medical profession. A surprisingly high proportion of breast cancers are actually discovered by women themselves, without the aid of anything more high-tech than their own familiarity with the way their breasts feel, month by month. The American Cancer Society admitted some twenty years ago that almost 90 percent of all breast cancers were actually initially detected by women themselves   (Ross 1987).

Although false positives do occur with clinical breast examinations, they are, perhaps surprisingly, less than half as common as they are with mammography. One study has shown that CBE is more sensitive (i.e., better able to detect abnormalities) than mammography in younger women with denser breast tissue. The same study found that CBE is better than mammography at detecting dangerous ‘interval’ cancers. Indeed, this study found that the combined use of CBE with mammography detected more abnormalities than either modality used alone (Elmore 1998).

The Canadian National Breast Cancer Screening study concluded that in women aged 50-59 years, "the addition of annual mammography screening to physical examination has no impact on breast cancer mortality." That is, even though mammography was able to detect cancers at a smaller size, before they became large enough to be detected by CBE or BSE, this still did not improve survival rates, because "the majority  of the small cancers detected by mammography represent pseudo-disease or overdiagnosis" (Miller, 2000).

This is not to suggest that there is no place for mammography in the detection of breast cancer. Far from it. Mammography certainly does have a place, and a useful place. As a diagnostic tool, it is the best we currently have. However, screening and diagnosis are two entirely different things.

Screening is intended to pick up possible abnormalities in otherwise healthy individuals, whereas diagnosis is the method whereby an abnormality, often initially detected by screening is more closely examined in order to identify its true nature (i.e., what its origins are, and whether the abnormality is benign or malignant, for example). The characteristics that make a good screening test are not by any means the same as those that are needed for diagnostic purposes.

The judicious and selective use of an imaging technique as a diagnostic tool in patients who have already been identified  as having a suspicious lesion is not at all the same thing as the blanket application of an imaging technique in the mass screening of an entire population.

In the headlong rush towards mass mammography, the value of really thorough clinical and self breast examination has been almost entirely eclipsed. As we have seen, there are distinct dangers and drawbacks to mass screening with mammography, and the standard recommendation of annual mammography for all women over 40 is badly in need of revision. Particularly in these younger women, in whom mammography is both more dangerous and less able to detect abnormalities, regular CBE and BSE  are of great importance (Baines 1997; Epstein 2001).

Thermography, or digital infrared imaging (DII), is a technique that uses infrared technology to identify abnormalities. It is able to detect subtle differences in the heat emitted by different areas within the breast tissue. Because malignant tissue has a higher metabolic rate than normal tissue, thermography picks up these areas even when they are extremely tiny – long before they are detectable on mammography, in fact.

As a screening method, thermography is not a replacement for mammography, but a useful adjunct to it. As noted earlier in this series, screening and diagnosis are two different things. Screening is intended to pick up possible abnormalities in otherwise healthy individuals, whereas diagnosis is the method whereby an abnormality, often initially detected by screening, is more closely examined in order to identify its true nature (i.e., what its origins are, and whether the abnormality is benign or malignant, for example). The characteristics that make a good screening test are not by any means the same as those that are needed for diagnostic purposes.

The major advantages of thermography are that it does not involve compressing the breasts, and that it does not use ionizing radiation. As noted above, it can also detect abnormalities at an earlier stage than mammography. However, heat changes in breast tissue can result from many different processes, not just from malignancy, and a positive thermogram is not specific for cancer.

False positives, in other words, are an inherent problem with thermography just as they are with mammography. Another problem is the fact that thermography  cannot locate the precise anatomical position of a lesion with accuracy; it still takes a mammogram or other diagnostic technique to pinpoint the exact site of an abnormal area within the breast.

The best use of thermography is therefore as a technique that can be used in conjunction with mammography and CBE/BSE. Because it can detect abnormalities earlier than mammography, it is particularly useful in identifying the need for further investigations (including mammography), and since it is so  non-invasive and so safe, it is an ideal method for routinely  monitoring women who are at added risk for breast cancer.

It is particularly useful, too, for younger women and those with dense breast tissue. For such women mammography is not only an inadequate imaging technique but also carries added risks, including lifetime cumulative radiation exposure, and the danger of an increased, rather than a decreased, risk of death from breast cancer (the so-called 'mammography paradox').

Although thermography has been approved by the US Food and Drug Administration (FDA), relatively few doctors know about it and the profession as a whole is not yet generally willing to accept its conclusions. In addition, few insurance companies will pay for this procedure.

Ultrasound, or sonography, which uses sound waves to create an image of the internal structure of the breast, is again typically used a diagnostic rather than a screening tool, although clinical trials are currently in progress to assess its value in screening. One of the drawbacks of older ultrasound techniques was that the hallmark 'microcalcifications' that accompany early breast cancer were not typically visible. However, newer techniques such as Doppler ultrasound have largely overcome this problem.

In addition, ultrasound can be very useful not only in imaging dense breast tissue (something mammography does not do well) but also in distinguishing between benign and potentially malignant lesions, thus sparing many women the need for a biopsy. It seems very likely that this non-invasive technique will come to occupy a prominent place in early detection of breast cancer, perhaps even supplanting mammography.

MRI (magnetic resonance imaging) is another technique whose value in breast cancer screening has perhaps still not been fully harnessed. In clinical trials MRI has proved to be more sensitive than mammography, ultrasound or CBE in detecting early cancers.

However, it has also proved to be even more susceptible to false positives than mammography. So while MRI, like thermography, has advantages in that it does not involve breast compression or exposure to radiation, it is not a replacement for mammography either. It does, however, have a definite role to play in screening, as an adjunct to CBE and mammography, particularly for younger women with denser breast tissue, and for those whose family history suggests an increased risk of developing breast cancer.

PET (positron emission tomography) scanning has not yet found a definitive place in breast cancer screening. PET is indeed a very sensitive method of detecting aggressive cancers and does not give rise to as many false positives as most of the other imaging methods. In the detection of recurrences in women who have been previously treated for breast cancer it has been shown to be superior to other techniques. However it is still not particularly useful for identifying marginally invasive lesions. In addition, PET involves the use of an injected radioactive contrast medium, and while the half-life of this material is extremely short – i.e., the exposure to radioactivity is relatively small – it is certainly not a procedure to be undertaken on a regular basis for screening purposes. Nor is PET by any means universally available or affordable.

An Ounce of Prevention

While mammography screening is universally portrayed as essentially a preventive practice, it is in fact nothing of the sort. It is a means of detecting lesions that are already present and growing. Before a lesion becomes detectable on a mammogram it has typically been present for an average of 8 years. The best that can be said for the role of mammography is that it is a modestly effective tool in the service of damage control.

Every cancer avoided is a triumph, and every cancer death a tragedy. While mammography may indeed be a useful (though far from perfect) screening tool, it cannot stop women developing breast cancer, and neither can it reliably prevent the majority of deaths from the disease.

Yet the American Cancer Society, the National Cancer Institute and the medical profession at large (all of which have strong ties to the multi-billion dollar mammography industry) continue to focus their education efforts exclusively on the detection of existing breast cancer via screening mammography (Epstein 2001). If instead of doing  this, they were to throw their considerable political and financial weight wholeheartedly into the effort to find and control the environmental triggers that contribute heavily to the incidence of this dread disease, we might see more substantial progress.