New test can better uncover hidden bre...( h nodes (slicing the nodes and staining...),Health

In current methods, pathologists look for cancer in slices of lymph nodes that have been stained and magnified under the microscope. They can spot cancer cells by looking at the shape of cells and the way they are clustered. While this technique is sensitive and reliable, if cancer cells do not have a typical shape or architecture or if there are very few such cells in a lymph node, the cancer might go unnoticed.

The new test significantly improves on the standard methods to detect cancer in the lymph nodes. It requires a mix of two substances, called antibodies. "These antibodies detect, with a high degree of accuracy, proteins that are present in breast cancer cells, but not present in the normal cells of the lymph node," Cote said. The antibodies are placed on the lymph node tissue, and if breast cancer cells are present, they will react with the antibodies - - producing a color change in the cancer cells that a pathologist can detect under the microscope. Even very small numbers of cancer cells, which usually are extremely difficult to identify by conventional methods, can be detected through this new technique.

To study the effectiveness of the new procedure, scientists examined lymph node tissue from 738 breast cancer patients. These patients were considered to have no evidence of metastases in their lymph nodes by conventional analysis. The lymph nodes were then tested with the antibody mixture to look for signs of occult, or hidden, cancer. Scientists found occult nodal metastases in 20 percent of the patients using the antibody technique. Occult metastases were more commonly found in lymph nodes from women with large breast cancer tumors, which have a higher risk of developing metastases. However, in some cases, metastases were even
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Contact: Alicia Di Rado
dirado@hsc.usc.edu
323 442 2830
University of Southern California
10-Sep-1999