DNA test may identify risk of breast cancer

January 09, 1995|By Newsday

A new test that involves looking for signs of damage in the DNA of breast cells may provide an early way to identify women at high risk for breast cancer, a research team in Seattle reported yesterday.

The studies, reported in the journal Cancer, are very preliminary and the test is not fully developed. But the results suggest that an accurate way may be found to measure the gene damage that leads to cancer, even before cancer can begin.

"We use a special type of microscope to look at the inner structure of the DNA molecule," said biochemist Donald Malins. "That allows us, for the first time, to look for changes at the molecular and atomic level in relation to cancer."

The test is based on shining infrared light through the DNA taken from a breast cell. The light's "signature" is altered according to how much damage has accumulated in the genes. In recent tests run on breast cells from 29 women who did not have cancer, 59 percent had DNA damage similar to what was seen in breast cancer patients.

The results, Mr. Malins said, "suggest that these women are at high risk for developing breast cancer in the future." Mr. Malins, of the Pacific Northwest Research Foundation and the University of Washington, said the high rate of DNA damage being seen could help explain the high rate of breast cancer in the United States.

He explained that the test is set up by analyzing the DNA from cancer cells and recording how much damage has occurred in their DNA. The cancer-prone DNA then serves as a "library" -- a cancer DNA data bank with which other DNA can be compared.

Making a comparison involves taking DNA from noncancerous breast cells, shining the infrared light through the DNA, and then assessing how much damage has been done.

"The closer you get to matching the cancer DNA library, the greater the risk you have of getting cancer," Mr. Malins said.

If such a test proves accurate, Mr. Malins added, "it means you have a way of predicting the disease at the earliest stages of cancer, before any cancer cells exist in the body."

According to molecular geneticist Richard Cawthon at the University of Utah, the new test "could be very important."

But, he said, "They need to go out and get samples in a blinded way and see if [the tests] turn out to be right. I'll believe it's useful if they go ahead and do the additional testing."

Dr. George Hemstreet III, a pathologist at the University of Oklahoma, said the new results "are very interesting," even though it is too early to tell if the technique will be useful.

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