Value of PSA Screening Questioned

Oct. 3, 2002 -- Nowadays, fewer men die of prostate cancer. Aggressive screening with the PSA test usually gets the credit. But now an interesting natural experiment raises doubts.

This "experiment" happened from 1987 to 1990. Blood tests for prostate-specific antigen (PSA) were just coming into widespread use. Medicare data for men aged 65-79 in those years show that the test was used very aggressively in the Seattle area, but not in Connecticut. More than five times as many men in Seattle got PSA screening. This led to 2.2 times more prostate biopsies and more than six times as many operations to remove the prostate gland.

This should have saved lives. But 11 years later, men in Seattle and Connecticut had the same rate of prostate-cancer death. Study leader Michael J. Barry, MD, is chief of general medicine at Massachusetts General Hospital and associate professor at Harvard Medical School. The findings appear in the Oct. 5 issue of the British Medical Journal.

"It's not that there was no PSA testing in Connecticut, but there was 5.4 times as much PSA testing in Seattle. We thought the population of Connecticut would pay the price for that, but apparently not," Barry tells WebMD. "It doesn't look like that pretty dramatic difference in intensity of testing made any difference in prostate cancer mortality."

PSA is a protein made by cells of the prostate gland. Blood levels of PSA go up when the prostate is enlarged. Sometimes this means nothing. But sometimes it means cancer. Only a biopsy can tell. Current guidelines from the American Urological Association call for annual PSA screening of all men after age 50. Black men and men with family histories of prostate cancer have a higher risk of the disease. They are advised to begin annual screening at age 40.

Prostate cancers usually -- but not always -- grow slowly. If a biopsy finds cancer, men have four standard options: wait to see if the cancer gets bigger, have surgery, have external-beam radiation treatment, or have tumor-killing radioactive seeds implanted in the prostate. These treatments can have many serious side effects, including impotence and urinary incontinence. Cryotherapy, where freezing temperatures are used to kill cancer cells, is another, less readily available, treatment option.

Some medical experts ask whether aggressive PSA screening is a good idea. Britain hasn't had an aggressive screening program, yet there's been a drop in prostate-cancer mortality similar to that seen in the U.S. An editorial co-authored by patient advocate Hazel Thornton appears alongside the Barry study. Thornton has received an honorary doctor of science degree for her work to make medical researchers more aware of patient needs. A cancer survivor herself, she questions whether screening is helpful for individual patients.