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Sunday, October 26, 1997

Breakthrough test for prostate cancer granted patent

SAN ANTONIO (AP) -- A patent was granted for a diagnostic prostate cancer test that someday may predict which patients require aggressive treatment.

The test, which was developed by researchers in San Antonio and at the National Institutes of Health, is a molecular probe that can detect extra copies of genes in tumor cells. The tumor cells are a clue that the tumor is fast-growing and should be treated aggressively.

"We would hope that, ultimately, this could be used in a hospital or clinic to give physicians information about which patients with prostate cancer had the worst type disease,' said John McGill of San Antonio, a molecular geneticist with the Cancer Therapy and Research Center's Institute for Drug Development.

Many prostate cancers are slow-growing, and in many elderly men, doctors prefer to forgo treatment and simply follow the patient closely.

Those treatments include surgery, radiation, hormonal therapy and castration -- all of which can leave patients incontinent and impotent. No effective method exists to diagnose whether a tumor is slow-growing or aggressive.

The new test is based on observations that patients with advanced or aggressive prostate cancer have extra copies of genes normally located on chromosome 8. Those extra bits of genetic material are called double minutes.

"Most normal cells would have two copies of every gene,' McGill said. "If suddenly you had 30 copies of a gene where you expected you had two copies, now there's a problem. Whatever that gene was making, it would give you 15 times as much material. That can cause problems.'

Since the gene plays a role in normal cell division, extra copies may contribute to the uncontrolled growth of cancer cells, McGill said.

The test needs additional study and development, he said. With a patent in place, the researchers hope to attract a corporate sponsor.

Prostate cancer is the most commonly diagnosed cancer in U.S. men, with some 334,000 new cases predicted this year, according to the American Cancer Society.

It is the second leading cause of cancer deaths among men, with 41,800 expected to die this year.