PROSTATE cancer gene profile may give doctors better diagnostic tool to treat disease

Wednesday, August 22nd 2001, 12:00 am
By: News On 6

Like detectives developing a profile of a killer, researchers have tracked down new clues to the genetic identity of prostate cancer. That could lead to better testing and tailoring of treatment to individual patients.

The researchers measured the activity of about 10,000 genes simultaneously in normal tissue and prostate cancers, discovering an activity profile for each type of tissue.

Their work revealed some 200 genes involved in the disease, said Dr. Arul Chinnaiyan, who directed the University of Michigan study appearing in Thursday's issue of the journal Nature.

``This is important, because it is most likely that many genes are involved in the development and progression of prostate cancer _ each controlling a different step in the process,'' he said.

Prostate cancer is the most common cancer diagnosed among men. Doctors typically rely on physical examination to detect prostate cancer but a blood test that became widely available in 1987, called the prostate specific antigen or PSA test, has helped in earlier diagnosis.

Unfortunately, the PSA test also gives many ``false positive'' results and is not as reliable as doctors would like, Chinnaiyan said.

In addition to a new means of detecting the cancer itself, the new study may lead to a way to determine whether it is relatively benign and slow growing or a very aggressive form that spreads quickly.

Such a test could, in turn, guide doctors in how aggressively to treat patients. It also could help doctors better answer worrisome questions typically asked by patients who want to know if surgery is necessary or the chances the disease will return, Chinnaiyan said.

He noted some of the genes identified in the study previously were linked to cancer but many others had not been associated with the disease.

Two of the new genes linked to prostate cancer are called hepsin and pim-1, which the researchers say may turn out to be markers that can be developed into a test.

More than 700 samples of prostate tissue were tested for hepsin in the study, and the highest levels were found in pre-cancerous cells. The lowest levels were found in benign tissue.

Another leading researcher says the study is only a first step toward a better diagnostic test.

``What's important here is that this test is not ready for routine clinical implementation,'' said Dr. Todd Golub, who specializes in the genetics of cancer at the MIT Center for Genome Research in Cambridge, Mass.

Results must be confirmed by other scientists, he said.

Golub said the standard means of detecting the disease, physical examinations, will remain essential.

But Golub praised the Michigan researchers for using ``DNA chips'' to study thousands of genes at once.

``It allowed them to look at genes they otherwise wouldn't have considered testing,'' he said.