The Future of Breast Cancer Screening (cont.)

  • Ductal lavage and ductoscopy. The idea behind these two methods is that certain cancers begin in the milk ducts of the breasts. In ductal lavage, a catheter is inserted through the nipple and into the milk ducts. A saline solution is emptied into the ducts, and then withdrawn. Then the cells washed out from the ducts are checked under a microscope. In ductoscopy, a catheter with a light at the tip is inserted through the nipple into the ducts and a dye is injected. The dye outlines the shape of the duct and an X-ray ideally shows whether there is an abnormal growth in the area.

  • Electrical impedance spectral imaging (EIS). Low-frequency electrical currents are applied to the breast, and an image is formed based on the theory that normal tissue and cancerous masses conduct electricity in different ways.

  • Microwave imaging spectroscopy (MIS). This device uses microwave energy that is similar to cell phone frequencies (but at a much lower level). The technique is particularly sensitive to water, and can detect areas where there is more of it. Tumors are thought to have more water and blood than regular tissue.

  • Near infrared (NIR) spectral imaging. This method is based on the idea that infrared light is sensitive to blood, creating an image of hemoglobin inside the breast. Knowledge of vascular activity is believed to help spot early tumor growth, and determine its stage.

    Researchers at Dartmouth College in New Hampshire are simultaneously studying four of these screening techniques: NIR, MIS, EIS, and MRE. If one or more of these methods are found to be promising, scientists might look into integrating the technologies into a single tool.

    "We're excited about the possibilities, but there's a lot to be worked out," says Keith Paulsen, PhD, principal investigator of Dartmouth's Breast Imaging Project.

    Clinical trials began April 2003, and may wrap up next summer. An interim analysis with official statistics on the success of each technique is due in the next couple of weeks; meantime, Paulsen is optimistic. "The projects are going well," he says.

    Next: Detecting cancer before it starts.

    Looking Into a Biological Crystal Ball

    Several studies are currently looking into the possibility of diagnosing breast cancer at the cellular level. There is hope that someday researchers will be able to identify a turning point when biological substances become cancerous, thus leading to development of methods for detecting warning signals.

    The National Cancer Institute alone has funded research into at least a half-dozen tests that involve examining typical and irregular proteins, molecules, genes, and other biological matter. One such large clinical trial in progress is a blood test. By analyzing concealed patterns of protein in blood, investigators propose being able to distinguish malignant tissues from benign ones.

    Although this blood test is currently being tested only for ovarian cancer, researchers are hopeful the technology, once proven, could be adapted to other cancers. If everything goes well, investigators plan to compare the outcome of the trial with other blood test research around the country of other cancers.

    One such study to detect breast cancer by looking at blood cells has already ended. The results? The blood test was 95% successful in spotting malignancies. The complete report is currently being reviewed for publication in a medical journal.

    "Everything looks extremely exciting...but we want to move cautiously," says Lance Liotta, MD, PhD, a principal investigator of the Clinical Proteomics Program, and chief of the laboratory of pathology at the National Cancer Institute.

    When could such a blood test become available? Liotta says that depends on three factors:

  • First, researchers must check the accuracy of the blood test by waiting to see if women develop cancer.
  • Second, those results must prove the test works reliably in large groups of women.
  • Third, the Food and Drug Administration must approve the test.

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