Make No Mistake PSA Is A Bad Screening Test for Prostate Cancer

Please don’t be confused with the recent reports about PSA testing; it is crystal clear that PSA is not a good test to screen asymptomatic men for prostate cancer. Although it has been used as a screening tool for more than 2 decades, it wasn’t until this week that the results of a clinical trial revealed that it does not save lives from prostate cancer (http://www.usatoday.com/news/health/2009-03-18-psa-prostate-cancer_N.htm#uslPageReturn). Remember, an elevated PSA is not diagnostic of cancer! An elevated PSA just starts a cascade of tests and procedures to determine whether cancer is present. If 100 men had their PSA measured, 15 will found to have elevated levels. Further testing of those 15 men would reveal that only 3 had cancer. Men have an overall 16% chance of being diagnosed with prostate cancer in their lifetime, but only a 4% chance of dying from the disease.

PSA was originally intended to be used as a tool to detect prostate cancer recurrence. Following prostatectomy after cancer diagnosis, men would be followed with periodic PSA screening. When the prostate is surgically removed (prostatectomy) PSA would be zero (because PSA is a protein that is produced only in the prostate), but if PSA was detected it meant that the cancer had returned.

Urologists turned it into a screening test for men with no symptoms of prostate cancer because, candidly, a positive test resulted in more invasive and expensive procedures to diagnose and treat cancer, many of which are inconsequential. The evidence that was available was that you were better off flipping a coin than doing a PSA test (because 3 out of 4 men with elevated PSAs were not found to have cancer). As the PLCO study revealed this week, 48 men had to be treated to save one man from dying of prostate cancer. Screening assymptomatic men with PSA was always controversial in the medical community, with the prestigious American Cancer Society withholding its recommendation for such a test.

The bottom line is to follow the recommendations by the USPSTF that PSA testing should be done only after you have all the information you need from your doctor to make an informed decision. Namely, 1. PSA is not diagnostic of prostate cancer. 2. If you have an elevated PSA your prostate will need to diagnose prostate cancer. 3. If you are diagnosed with cancer you will have to choose a treatment option which could have serious side effects for a cancer which most likely would not result in your death (remember the PLCO trial showed that 48 men had to be treated to save one from dying from prostate cancer). Such side effects include, among other things, impotence and incontinence. Another option is to do watchful waiting. Since prostate cancer is slow growing, taking as much as 10 years to become clinically apparent (if it is going to do so at all), men have the option of waiting for treatment to see whether the tumor actually progresses or not, still leaving plenty of time for successful treatment down the road. Watchful waiting may include periodic PSA and DRE testing and more biopsies.

If you do go ahead with PSA screening and are subsequently diagnosed with prostate cancer, get a second opinion. If the pathologist doesn’t see enough prostate cancers where it has become routine in his practice, he may not have the experience to make an accurate diagnosis. Also, if the diagnosis is confirmed and you decide to go ahead with treatment be sure your doctor has done the procedure hundreds of times. For example, that it takes at least 250 prostatectomies for a urologist to  be an expert.

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