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Thirty years ago medical researchers discovered a substance produced in escalating levels by the prostate gland as cancer developed. This substance, prostate specific antigen, or PSA, became the basis for a test to detect prostate cancer and the PSA test has been controversial ever since
The latest development in the long-running medical debate about the effectiveness of the PSA test was published March 26 in the New England Journal of Medicine.

In a trial involving 76,693 U.S. men, including 2,202 from Alabama, researchers reported that increased screening with PSA tests failed to decrease death rates from prostate cancer. Also, more PSA testing led to unnecessary treatments, often with serious side effects, researchers reported.

"More is not better," said Dr. Mona N. Fouad, a co-investigator from the University of Alabama at Birmingham, one of 10 medical centers participating in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. "What this study says is we need a better screening tool."

Oddly, many studies have shown that PSA testing does detect cancer, and this study was no different, Fouad said. "It was effective in finding more cancer," Fouad said. "But if it was really effective, it would have saved more lives."

Here's the problem: The PSA test detects prostate cancer and noncancerous conditions that push up PSA levels. And it is unable to gauge the severity of the cancer it detects. Prostate cancers can vary significantly in their aggressiveness, and there is no good test to sort out the quick-and-lethal cancers from the cancers that grow slowly and aren't a threat to life.

Health authorities say that it makes no sense to treat them all with surgery, radiation or chemotherapy. These treatments carry significant side-effects, such as incontinence and impotence. "If you over-diagnose and over-treat, you have more potential to harm," Fouad said.

The U.S. Preventive Services Task Force, a group of experts that examines evidence and makes recommendations on procedures like the PSA test, has shied away from the issue other than to say men 75 or older or with a life expectancy of less than 10 years need not get PSA tests.

Many doctors disagree with setting a specific age for cutting off PSA tests, and other groups feel differently about PSA tests in general, seeing them as a practical way to catch prostate cancer early. For instance, the American Cancer Society recommends PSA tests annually, starting at age 50.

But everybody agrees that men should be made aware of the benefits and risks involved with getting a PSA test - it may lead to a series of tough treatments that may or may not extend their lives.

"We just don't know," Fouad said. "Hopefully they'll be able to come up with another biomarker test so we can identify those tumors that are high risk, rather than those tumors that men live with for years."

In the meantime, men should talk with their doctors about the PSA test, and they should consider risk factors, such as a family history of aggressive prostate cancer, Fouad said.

"It has to be an individual decision between the physician and the patient," she said. " It has to be about the trade-offs, and it has to be informed consent."

Source: UAB