WASHINGTON (AP) -- Many men over 60 are receiving unnecessary surgery and other treatments for prostate cancer even though the disease is unlikely to progress far enough to cause health problems, according to one analysis.

A study in the Journal of the National Cancer Institute examined the use of a blood test to find prostate cancer in a group of patients 60-84 over a 10-year period. It concluded that 29 percent to 44 percent of the men were "over-diagnosed."

Those patients may have received surgery or radiation treatment for prostate cancer that would never have progressed so far that it threatened their health, said Ruth Etzioni, a biostatistician at the Fred Hutchinson Cancer Research Center in Seattle.

"Over those 10 years, of the men diagnosed as a result of the PSA test, up to 30 percent may have been treated unnecessarily," said Etzioni.

The PSA test measures the level of a prostate-specific antigen in the blood. A high number may suggest prostate cancer.

Etzioni said prostate cancer is a slow-moving disease. Many older men may have prostate tumors that will never become life-threatening because they will die of other causes before the cancer has a chance to spread.

Over-diagnosis for prostate cancer is a concern because active treatment - surgery or radiation - can have debilitating side effects. Etzioni said that about 80 percent of men who have prostate cancer surgery experience impotence, often permanently. For those treated with exterior beam radiation, the impotence rate three years later is about 43 percent. About 10 percent are incontinent after surgery, she said.

The study is based on a computer model of 2 million men. It projected the long-term effect on those men of early diagnosis of prostate cancer as the result of using the PSA test.

The projections from the computer study were then compared with NCI cancer registry data. The computer estimate of over-diagnosis was consistent with the observed data, the authors said.

Dr. Darracott Vaughan, a New York urologist and a recent president of the American Urological Association, said that the Etzioni study fails to address the effect of PSA tests on the rate of survival among prostate cancer patients. Such studies are not yet complete, he said, and until they are "it's anybody's guess" about whether prostate cancer is being over-diagnosed.

He said some prostate cancer patients - those who have low PSA tests or who may be expected to die within 10 years - are now treated with "watchful waiting" instead of aggressive surgery or radiation. But he said the level of treatment should be a patient decision.

Vaughan said that PSA tests help find patients when they have a 75 percent chance of being cured of the disease. Without the test, the cancer is often not detected until symptoms develop; by then, it is 75 to 80 percent incurable because it has spread to the bones or other organs, he said.

"Our position on PSA is that we find out and then inform the patient," said Vaughan. "We give them the data about being at low risk, intermediate risk or high risk" and let them make the treatment decision.

Copyright 2002 The Associated Press. All rights reserved.