SIGNIFICANT BREAKTHROUGHS IN EARLY CANCER DETECTION, announced at last week's APS March Meeting in Minneapolis, apply physics techniques in new ways to detect disease. Employing light-scattering spectroscopy, in which one studies the colors deflected by an illuminated object, Michael Feld (617-253-7700, msfeld@mit.edu) and colleagues at MIT have developed a method for detecting the earliest signs of cancer in the epithelium, the layer of tissue lining the inner surfaces of the body such as the colon and bladder. An estimated 85 percent of all cancers begin in the epithelium, which often serves as the body's first line of defense against disease.

Usually, pathologists must biopsy epithelial tissue and rely on their experienced (but subjective) eyes to find signs of early cancer. Demonstrating a less invasive, more quantitative approach, the MIT researchers employ a narrow fiber-optic probe to shine white light onto epithelial tissue, and collect the light that the tissue deflects directly back to the probe. With this backscattered light, the MIT researchers could measure the index of refraction and spectral content in different regions of tissue.

This enabled them to map out areas (see Physics News Graphics) with such trouble signs as abnormal crowding of cells, enlargement of cell nuclei, and an increase in genetic material known as chromatin. Having successfully identified pre-cancerous colon and esophageal tissue in clinical tests, the researchers believe that their technique will reach the commercial market in the next few years.

Also at the meeting, Paul Gourley of Sandia (505-844-5806, plgourl@sandia.gov) presented a dime-sized "biocavity laser" that can detect cancer in the blood by examining only a few hundred cells--equal to about a billionth of a liter. (See http://www.sandia.gov/media/NewsRel/NR/pnu/2000/candetec.htm)