COMMENTARY

PSA Screening: the debate between belief and evidence.

"It is time for the storm to abate and for a gentle wind of change, carrying hard-earned facts, to clear the air" Glassock and Winearls (1) 

Today’s commentary is about the age-old tension between belief and evidence. How much of our clinical practice should be governed by what we believe versus what the evidence shows?

I am going to discuss the screening for prostate cancer because this past week the United States Prevention Task Force (USPSTF) recommended against the use of the prostatic specific antigen (PSA) in screening for prostate cancer. There has been quite extensive news coverage as well.

The USPSTF states that: “The common perception that PSA-based early detection of prostate cancer prolongs lives is not supported by the scientific evidence. The findings of the two largest trials highlight the uncertainty that remains about the precise effect that screening may have, and demonstrate that if any benefit does exist, it is very small after 10 years. The European trial found a statistically insignificant 0.06% absolute reduction in prostate cancer deaths for men aged 50 to 74 years, while the U.S. trial found a statistically insignificant 0.03% absolute increase in prostate cancer deaths (2,3). A meta-analysis of all published trials found no statistically significant reduction in prostate cancer deaths (4)."

The report goes on: “At the same time, over-diagnosis and overtreatment of prostatic tumors that will not progress to cause illness or death are frequent consequences of PSA-based screening. Although about 90% of men are currently treated for PSA-detected prostate cancer in the United States—usually with surgery or radiotherapy—the vast majority of men who are treated do not have prostate cancer death prevented or lives extended from that treatment, but are subjected to significant harms”.

The USPSTF concludes that there is moderate certainty that the harms of PSA-based screening for prostate cancer outweigh the benefits. USPSTF recommends against prostate-specific antigen (PSA)-based screening for prostate cancer.

As is usual in these types of debate opinions are heated and motives can be questioned on both sides. [This is true for what happens in the kidney community also]. An example of the heat being generated is exemplified by the NY Times article below

“The American Urological Association issued a statement saying that the recommendation “will ultimately do more harm than good.” Many urologists reacted angrily. “All of us take extraordinary issue with both the methodology and conclusion of that report,” said Dr. Deepak Kapoor, chairman and chief executive of Integrated Medical Professionals, a group that includes the nation’s largest urology practice. “We will not allow patients to die, which is what will happen if this recommendation is accepted.” He and other urologists said that the P.S.A. test is just one part of an overall strategy that, in the hands of well-trained doctors, can help prevent death and other consequences of cancer.”

The article goes on: “Treating patients with prostate cancer is a highly profitable business in the United States, and much of the practice of urology is dedicated to this fight. If men no longer get screened routinely, urologists will see a steep decline in patient visits and income. But Dr. Kapoor rejected the notion that profit plays any role in his defense of screening.

“But Dr. Otis Brawley, chief medical officer of the American Cancer Society, suggested that is what doctors like Dr. Kapoor are doing. “We in medicine need to look into our soul and we need to learn the truth,” he said. “If your income is dependent on you not understanding something, it is very easy not to understand something.” 

Remind you of something? Using epo in CKD patients? Dialysis dose? 

References

1. Glassock RJ, Winearls C. Screening for CKD with eGFR: doubts and dangers. Clin J Am Soc Nephrol. 2008 Sep;3(5):1563-8. Epub 2008 Jul 30. PubMed PMID: 18667744.

2. Chou R, Croswell JM, Dana T, Bougatsos C, Blazina I, et al. Screening for prostate cancer: a review of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med. 2011 Oct 7. [Epub ahead of print]


3. Lin K, Croswell JM, Koenig H, Lam C, Maltz A. Prostate-Specific Antigen-Based Screening for Prostate Cancer: An Evidence Update for the U.S. Preventive Services Task Force. Evidence Synthesis No. 90. AHRQ Publication No. 12-05160-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2011.

4. Ilic D, O’Connor D, Green S, Wilt TJ. Screening for prostate cancer: an updated Cochrane systematic review. BJU Int. 2011;107:882-91.