A new diagnostic method could make testing for breast cancer easier, quicker and cheaper, according to a Harvard Medical School physician who developed the method.

Today's issue of Cancer Research describes the new technique for measuring the activity of a protein which suppresses cancer, especially breast tumors. The test was developed by Medical School researchers led by Assistant Professor of Pediatrics Dr. Stephen H. Friend.

The new technique detects changes in the protein produced by p53, believed by many experts to be a tumor suppressor gene. Mutations in p53 have been linked to an increased predisposition in many patients for a number of tumors, including breast cancer.

Scientists hope the new technique will eventually allow doctors to screen large numbers of people in hours--rather than weeks--for high risks of cancer. This knowledge should permit doctors to monitor high-risk patients sooner and begin cancer treatments earlier.

But a spokesperson at Massachusetts General Hospital, where the research was conducted, cautioned yesterday that the finding does not mean women with a family history of breast cancer should immediately request the test.

"There isn't a test that's ready to be done tomorrow on patients," spokesperson Martin S. Bander said. "The test has really only been worked out in the laboratory."

The new technique allows scientists to directly analyze the p53 protein, rather than perform the painstaking procedure of sequencing each base pair of p53 DNA to search for mutations.

And because the new method directly measuresthe protein, it avoids the possibility ofdiscovering gene mutations which do not actuallydisrupt protein activity. Such "silent mutations"are common and do not cause any changes in proteinefficiencies.

Calling the technique "a major conceptualbreakthrough," Friend said yesterday it "shouldeventually be applicable to other tumor suppressorgenes." In particular, two other tumor suppressorgenes, one for childhood kidney cancer and one forchildhood eye cancer, may be subjects of futuretests