New Prostate Cancer Test May Detect More Tumors

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New Prostate Cancer Test May Detect More Tumors

By Brown

Washington Post Staff Writer

Thursday, April 26, 2007; Page A03

An experimental blood test for prostate cancer may help eliminate tens of

thousands of unnecessary biopsies at the same time that it detects many

tumors that are now missed by the test commonly used, its developers said

yesterday.

PSA, the current test, measures a protein normally produced by the prostate,

while the experimental one, called EPCA-2, detects a chemical made

principally in cancerous tissue.

Prostate cancer, the most common malignancy in men, is one of the more

perplexing areas of medicine. Physicians are unsure how to find it and when

to treat it.

Today, about 80 percent of prostate biopsies find no tumor -- a percentage

that is rising as physicians become more aggressive in searching for the

disease.

" We hope this will minimize the number of unnecessary biopsies, " said

H. Getzenberg, a molecular biologist at s Hopkins Hospital who developed

the new test, which is still under study and not yet commercially available.

A description of it appears today in the journal Urology.

" It's an exciting new marker, " said G. Sanda, a urologist at Harvard

Medical School. " There certainly is a need for a better test than PSA.

Everyone accepts that. " His view was echoed by Gerald L. Andriole Jr., chief

of urologic surgery at Washington University School of Medicine, who said

that " if the data hold up, this marker will be a substantial improvement

over PSA. "

The PSA test casts a net that is too big and too full of holes. Finding a

replacement that catches fewer healthy men, but more of those who do have

cancer, would help settle at least one of the clinical conundrums concerning

prostate cancer.

The new test is being developed by researchers at s Hopkins Hospital and

Onconome Inc., a Seattle-based biomedical company. It could become

commercially available in 2008.

Prostate cancer is diagnosed in about 230,000 American men each year, and

about 30,000 die of it. The death rate is 2.5 times higher among blacks than

among whites.

At the moment, men are screened for the disease in two ways -- by a rectal

exam and by the PSA (prostate-specific antigen) test. If a lump is detected

or if the PSA is above 2.5 (nanograms per milliliter of plasma), most

physicians will suggest a biopsy.

EPCA-2 is a protein that is part of the " nuclear matrix, " the scaffolding

inside a cell's nucleus that helps it copy its genes. The Hopkins

researchers measured it in different groups of men whose cancer status was

known.

They tried the new test on 30 men with PSA readings above 2.5 and in whom

biopsies found no cancer. All had normal EPCA-2 readings (below 30 ng per

ml.). This suggested that the test may eliminate many of the

" false-positive " PSA results -- readings that are abnormal but apparently do

not denote cancer.

On the other hand, the EPCA-2 test appears able to detect cancer even when

the tumor is small. It identified 36 out of 40 men who had cancer confined

to the prostate gland, and 39 out of 40 men in whom the tumor had spread. It

also identified many men -- 14 out of 18 -- who had cancer but whose PSAs

were normal.

This last group is especially worrisome to physicians. A study published

three years ago found that about 12 percent of men with normal PSA readings

have cancer.

The new test is not perfect, though. Getzenberg and his colleagues tried it

on 35 men with severe " benign prostatic hypertrophy " -- enlargement of the

prostate that sometimes makes the PSA go up but is not cancer. In eight of

them, the EPCA-2 was high, suggesting that the EPCA-2 test would flag some

men who turn out not to have cancer -- although probably not as many as the

PSA test does.

The new test will not help solve the other major clinical uncertainty in

prostate cancer. It is unclear who will clearly benefit from aggressive

treatment and who are likely to be able to live a normal life if the tumors

are simply followed and removed only if they begin to cause symptoms.