Diagnosis

Dense Breasts? Breast Cancer Screening Tools Are Getting Better

PJ Hamel Health Guide May 20, 2007
  • It’s long been known that the denser a woman’s breast, the more difficult it is for a standard mammogram to pick up a tumor. On a mammogram, fat tissue is dark colored; breast tissue is light colored, as is a tumor. The less fat in a woman’s breast (the “denser” it is), the harder it is to see cancer on a mammogram. Recent studies have also shown that women with extremely dense breasts are at four to six times the risk for breast cancer as women with non-dense (high-fat) breasts. Thus the discovery of an effective tool for screening women with dense breasts has become even more critical.

     

    While a breast MRI is currently the best diagnostic tool for identifying a tumor in a woman with dense breasts, it’s not widely used, due to its relative complexity and expense in comparison to a standard mammogram. An MRI can cost up to 10 times as much as a mammogram. And, while we’d like to think that money doesn’t play a role in what kind of health care we receive, the reality is that it does. Insurance companies pay for procedures, and they understandably don’t want to routinely pay for an MRI vs. a mammogram. Nor, if you’re uninsured, do you.

     

    Now, two new alternatives/adjuncts to mammography have appeared on the horizon: one that could be available relatively soon, and one needing much more testing. The first, molecular breast imaging, is proving sensitive enough to detect tiny tumors, tumors of less than 10 millimeters that are virtually impossible for standard mammograms to detect in women with dense breasts.


    It’s an entirely new screening method, using “gamma cameras,” which produce an image not affected at all by dense vs. fatty tissue. The gamma camera is also a much more comfortable way to be screened. Unlike the “big squeeze” you get with a mammogram, your breasts are only lightly compressed, just enough to hold them steady for the camera.


    In women with dense breasts, a standard mammogram is accurate in picking up tumors only 30% to 50% of the time. Preliminary testing has shown that molecular breast imaging using gamma cameras is 93% accurate in picking up tiny tumors in dense breasts. A trial of molecular breast imaging is ongoing, and is expected to be completed within 2 years.

     

    A second new technology, one that measures electrical resistance in tissue to detect tumors, is gaining momentum, but is still fairly distant. An article in the Massachusetts Institute of Technology’s Technology Review notes that Z-Tech, based in Westford, Massachusetts, recently completed international trials involving an “electrical impedance” screening device on 3,500 subjects at 28 different sites. And “preliminary results indicate that the device catches more cancers and has fewer false positives than film mammography, most notably in patients younger than 50 years of age,” notes the Review.

     

    How does it work? Very minor electrical impulses are pulsed through your breasts via electrodes hooked up to a computer. As the electricity flows, if it hits a tumor it’ll flow more rapidly, a fact the computer picks up and records. Thus, if the data from one breast is significantly different than that from the other, “there’s a high probability it’s cancerous,” according to Z-Tech CEO Steve Nakashige.


  • Its upside? It uses harmless electricity, rather than x-rays; it’s painless and quick; and it doesn’t require a radiologist to read the results. Its downside? It can only determine if cancer is present: it can’t locate a tumor, nor tell you how big it is. And, thus far, it’s coming up an unacceptable number of false-positive readings. Still, advocates are saying it could find a niche alongside mammography for women with denser breasts. Z-Tech plans on launching a screening version of its product in Asia and Europe this year, and in Canada in 2008. Stay tuned.