STUDY FINDS FALSE BREAST CANCER TESTS.

Byline: David R. Baker Daily News Staff Writer

Women receiving annual mammograms face a 49 percent chance that in a decade of tests, one will be a false alarm, according to a study published today.

The study confirmed what many doctors and women have long known about the accuracy of mammograms, which are the first line of screening for breast cancer. But while the study's authors called on doctors to warn patients about the possibility of erroneous results, they stressed that women should continue to take the tests.

``Mammograms are the one thing that we know can save lives from breast cancer,'' said co-author Mary B. Barton, a researcher at Harvard Medical School.

The study, authors said, should help educate women about their chances of receiving a ``false positive,'' a mammogram result that raises the possibility of cancer in a patient who later turns out to be healthy.

Doctors noted that many other kinds of cancer tests also yield false positives because they are designed to make sure no problems are missed.

``You have to err on the side of, we don't know what this is, and all screening tests have that problem,'' said Dr. Richard Reitherman, chairman of the American Cancer Society's mammography screening project.

The study examined medical records of 2,400 women between 1983 and 1993, looking at the number of times those who received mammograms and clinical breast exams were called back for further tests. In most cases, the extra tests found no evidence of cancer.

But Barton noted that for many women in this situation, the clean bill of health comes only after days or weeks of worry. The mere prospect of breast cancer can conjure up fears of mutilation and dying young, she said.

``When women hear that they have an abnormal mammogram, there's a lot of anxiety that goes with it,'' Barton said.

Jurate Sepikas, 48, of Granada Hills endured weeks of uncertainty this spring when doctors found three suspicious ``shadows'' on a mammogram of her left breast. After a biopsy, the spots were found to be fibrous cysts, not cancer.

``When I was waiting for my test results, I jumped whenever the phone rang,'' she said. ``My biggest concern was, what was I going to tell my mom and my son?''

Previous studies have found that about 10 percent of mammograms raise enough questions to warrant further tests: either more X-rays, ultrasound or biopsies. But even if the request for more tests sparks anxiety in patients, doctors said Wednesday they would rather be overly cautious than risk letting a case of cancer go undetected.

Women receiving their first mammogram stand the greatest chance of being called back for more tests, since doctors don't have earlier X-rays for comparison, said Lawrence Bassett, director of the Iris Cantor Center for Breast Imaging at the University of California, Los Angeles.