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The PSA Test: What it is(05/04/2004) by Richard Spark, MD
Initially, the PSA test was greeted with great enthusiasm. Both the American Cancer Society and the American Urological Association encouraged doctors to include the PSA as part of the annual exam for all men over the age of fifty. However, as experience and disappointment with the PSA increased, others like the U.S. Preventive Services Task Force, the Canadian Task Force on Periodic Health Exam, and the Canadian Urologic Associations have issues stern warnings opposing routine PSA screening. Many are now questioning whether the PSA test does more harm than good.
How could a test to detect cancer at its earliest, most curable stage be harmful?
- The PSA is not specific -- many men with elevated PSAs do no have prostate cancer at all, whereas some men with "normal" PSAs do.
- An elevated PSA invariably triggers a chain reaction of additional costly diagnostic tests, including prostate ultrasound, prostate biopsy, and if the biopsy shows prostate cancer cells, it is decision time.
- When a man has an elevated PSA level and his prostate biopsy shows cancerous cells, treatment is usually recommended. Prostate surgery, radiotherapy, and/or surgical and medical castration may be considered.
But we are getting ahead of ourselves. First, some basic principles are in order.
To be useful, any diagnostic test must have a high degree of specificity. This means that when abnormal results occur, the test must identify a specific problem. If a man's blood pressure is consistently elevated, he has high blood pressure, or hypertension. If his red blood cell count is low, he has anemia. Both the blood pressure test and the red blood cell count have a high degree of specificity. An elevated blood pressure always indicates the presence of high blood pressure, or hypertension, just as low red blood cell count indicated the presence of anemia. But a high PSA level does not always indicate the presence of a prostate cancer, and a low PSA level is no guarantee that there are no cancerous cells within a man's prostate gland. Thus, the PSA lacks specificity.
To find out what an elevated PSA means, click here.
From the book, Sexual Health for Men: The Complete Guide. © 2000 by Richard
F. Spark, M.D. Reprinted by permission of Perseus Publishing. All rights reserved.
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