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                           JeffNEWS, May 1, 1995
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Highly Specific Biochemical Marker Found in Breast Cancer
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A protein identical to prostate-specific antigen (PSA), a highly specific
biochemical marker of the prostate gland found in the blood and used to
diagnose and monitor prostate cancer, was recently found to be produced in
approximately 30 percent of female breast tumors in a collaborative study
at the Jefferson Cancer Center (Jefferson Medical College) and the
University of Toronto. The presence of PSA in breast tumors holds promise
as a new, additional biochemical marker for breast cancer prognosis. It may
also determine whether breast cancer has disseminated throughout a patient's
body and can monitor a patient's response to treatment. PSA produced by the
prostate gland is currently used for diagnosis, prognosis and management of
patients with known prostate cancers.

Using highly sensitive and specific genetic tests, the researchers
determined that approximately 30 percent of breast tumors produce a protein
identical to PSA - a discovery that, for the first time, provides a link
between the most common cancer in men (prostate) and the most common
cancer in women (breast).

In the near future, the presence of PSA in breast tumors may have potential
applications for breast cancer prognosis, selection of therapy and the
design of new treatments. "The presence of cancer cells expressing PSA in
the blood means the tumor is shedding metastatic cancer cells into the
blood, some of which may cause metastases in other parts of the body," said
Carlo M. Croce, MD, chairman of Jefferson's department of microbiology and
immunology and director of the Jefferson Cancer Institute and the Jefferson
Cancer Center. "PSA is important because it gives us a way to measure the
level of invasiveness of cancer in at least 30 percent of patients - the
ones in whom breast cancers express PSA."

Preliminary evidence suggests that the expression of PSA is a relatively good
prognostic indicator. With breast cancer, expression of PSA is generally
associated with a lower degree of malignancy than if the tumor did not
express PSA. "Breast tumors which produce the protein have much better
outcomes than tumors which do not produce it," said Eleftherios Diamandis,
MD, deputy chair of the University of Toronto's department of clinical
biochemistry. "It is only when tumor cells lose their ability to produce
PSA that they become more aggressive. We envision that in the near future
this particular protein will be measured in all breast tumors that are
removed from cancer patients during surgery."

This research was presented at the Annual Meeting of the American Association
for Cancer Research, which took place March 18 through 22, 1995, in Toronto,
Ontario.

This collaborative research was supported by a National Institute of Health
Outstanding Investigator Grant to Jefferson's Dr. Croce and by Nordion
International, the Medical Research Council, Toronto Hospital, Mount Sinai
Hospital, Cancer Research Society, Inc., and the Canadian Breast Cancer
Foundation, Ontario Chapter.


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Information provided by:  Editor, JeffNEWS
                          (215) 955-6204
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