To Screen or Not to Screen? Prostate Cancer Screening: Why It's Not for Every Man

To the Editor:

For all diseases that limit our lives both qualitatively (morbidity) and quantitatively (premature mortality), those that we diagnose based on symptoms represent just "the tip of the iceberg." Virtually all disease has an asymptomatic phase, ie, the portion that lies beneath the surface.

Many diseases, perhaps most, have a spectrum of seriousness. Some cases of the disease will be very aggressive, resulting in sickness or death in a short time. Others may never become symptomatic, or may cause problems that are quite manageable and never lead to serious illness or death. There is often the assumption that time is the only difference between visible and invisible disease; that all undetected cases will eventually become symptomatic and have the same consequences as those detected from symptoms. This is not true. Biologically less aggressive disease is more likely to lurk beneath the surface for a longer time, sometimes indefinitely. If we look beneath the surface to find asymptomatic disease, we may find a very different spectrum of seriousness than we find with symptomatic disease. Usually we are not able to discern this difference, even with tests.

Looking for, detecting, and treating disease that lies beneath the surface always carries risk of harm. Ideally, before we go fishing, we should have good science to assure us that finding this disease before symptoms occur does more good than harm. Unfortunately, this is often not true, and there is no better example than prostate cancer.

• Asymptomatic prostate cancer is common. The best estimate for men aged 50-75 is that 25% of the population has it. If we look for prostate cancer, we will find it. If we find it, most men elect to treat it.

• The range of seriousness of prostate cancer is very large. Most asymptomatic prostate cancer will never become symptomatic. On the other hand, some prostate cancer is very aggressive, leading to death in a relatively short time after becoming symptomatic.

• Treatment is not benign. Roughly 1 in 300 men will die from complications of the treatment, most will have sexual dysfunction, and a significant minority will have bothersome urinary incontinence.

• We simply do not have the science to inform us of the balance of benefits and harms of looking beneath the surface for asymptomatic prostate cancer. It is wrong for us in medicine to suggest that we know prostate cancer screening results in either a better or longer life for those we screen. It is equally wrong to imply that we know it does not. Studies are being conducted that should shed more light on the issue.

My approach to patients includes a brief description of what we know and what we do not know, and the potential benefits as well as the potential harms of screening. It almost always starts with me saying:

"I would like to discuss screening for prostate cancer with a blood test called a PSA. The PSA test is a source of significant scientific controversy. I can highlight this controversy by telling you that I personally would not have the test, but I could send you to any urologist in this community and they would order it without discussion."

I end the conversation with:

"I am going to describe two people, and if you can tell me which of the two you are most like, I can tell you whether you should have a PSA."

On one end of the spectrum are those who say, "Look, Doc, I feel well. Unless you're certain you can do me more good than harm, leave me alone." On the other end, people say, "I am afraid of cancer, I worry about cancer, if I have a cancer I want to know about it and do something about it. I understand that there are both risks and uncertainties."

Obviously, with the knowledge we have today, the first group should not have a PSA and the second group should.^[1]

Michael LeFevre, MD
Professor, Department of Family and Community Medicine
University of Missouri School of Medicine
Columbia, Missouri
lefevrem@health.missouri.edu

Reference

1. LeFevre M. Prostate cancer screening: Why it's not for every man. Medscape J Med. 2008;10:124. Available at: http://www.medscape.com/viewarticle/574168 Accessed June 17, 2008.

Medscape J Med. 2008;10(8):181 © 2008  Medscape

Cite this: To Screen or Not to Screen? Prostate Cancer Screening: Why It's Not for Every Man - Medscape - Aug 03, 2008.