Most of my male patients are confused about all the recent information for and against prostate cancer screening using the PSA blood test. What’s the latest information and how should you react to it?
Another review has been published that does not support routine prostate cancer screening using the PSA blood test. Add this new information to the fact that the American Cancer Society and other major medical groups do not recommend routine prostate cancer screening for men at average risk and you have recommendations that should change the practice of many primary care physicians.
Widespread prostate cancer screening substantially increases the diagnosis of prostate cancer, but does not provide much evidence for a survival benefit, according to this new review.
Prostate-specific antigen (PSA) screening reduced prostate cancer-specific mortality risk by a “barely significant” 20% in the best-case-scenario clinical trial evidence, Ian M. Thompson, MD, of the University of Texas Health Science Center in San Antonio, and colleagues reported in the July/Aug. issue of CA: A Cancer Journal for Clinicians.
But, according to a report in MedPage, this small shift in lifetime risk from 3% to 2.4% came at the expense of an increase in risk of diagnosis from 6% to 9% without screening to at least 17%, and even more than 20% in a heavily screened population.
Unresolved issues with the PSA threshold also argue against the efficacy of screening, the researchers noted.
The cumulative evidence supports a recommendation against mass screening, rather than justifying its current common use in the U.S., said review co-author Otis W. Brawley, MD, of the American Cancer Society in Atlanta.
PSA screening should only be done in a “shared decision-making” setting between individual men and their physician, he recommended in an accompanying editorial with Peter Boyle, PhD, of the International Prevention Research Institute in Lyon, France.
“For nearly two decades, testing has been based on blind faith in early detection as opposed to being based on evidence of a decrease in mortality as observed in well-designed clinical trials,” they wrote.
Although it may be hard to put the PSA-testing genie back in the bottle, they cautioned: “If we are to stem the spiraling costs of healthcare, we must move toward the use of evidence-based rather than the faith-based or profit-based practice of medicine.”
An estimated 55% of all men 50 and older get annual PSA screening, with about 75% tested at some point in their lifetime.
This has had a dramatic impact on incidence rates for prostate cancer in the U.S., as the lifetime risk of diagnosis more than doubled after introduction of screening in the 1980s (7.3% in 1977 to nearly 17% in 2005).
However, simply finding more cancers is a poor goal in prostate cancer, which is “virtually ubiquitous in men as they age,” Dr. Thompson’s group said.
The primary aim from a public health standpoint is to reduce the risk of death from prostate cancer or at least reduce its morbidity or related healthcare costs, they said.
Indeed, since 1993 — just four or five years after screening began — there has been a continual decline in the age-adjusted prostate cancer death rate from 39.3 per 100,000 to 24.6 in 2005.
But attribution bias may be at work, the researchers noted.
“The decrease in prostate cancer mortality, occurring just four to five years after screening began, is difficult to attribute to screening when dealing with a disease of such a long natural history,” Dr. Thompson’s group wrote.
Alternative explanations for some, if not most, of the decline in mortality are the significant improvements in surgery, radiation, and use of hormonal therapies during the same period as screening proliferated, they said.
Computer models suggest that 29% to 50% of screen-detected prostate cancers would not have become clinically significant and were therefore overdiagnosed.
Only about 10% of men with localized prostate cancer opt for active surveillance rather than treatment, which carries a substantial risk of sexual, urinary, and bowel complications.
“The best way to address the issue of whether prostate cancer screening saves lives is through a well-designed, well-conducted, prospective randomized clinical trial,” the investigators said.
Four have been published:
- The Quebec study found a 16% excess of deaths in men randomized to screening compared with a control group not invited to screening.
- A Swedish trial found a 47% higher rate of diagnosis and 4% higher risk of death from prostate cancer in men randomized to screening compared with those not offered screening.
- Interim analysis of the U.S. Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening trial revealed no significant difference in mortality (rate ratio 1.13 for more versus less intensive screening, 95% confidence interval 0.75 to 1.70).
- Interim analysis of the European Randomized Study of Screening for Prostate Cancer (ERSPC) revealed a mortality rate ratio 0.80 favoring screening (P=0.04) but a near doubling in incidence.
Thus in the “best case scenario” as indicated by the ERSPC, the number needed to screen was 1,410 and 48 additional cases of prostate cancer needed to be treated to prevent one prostate cancer death.
“This means an average man who gets screened is 48 times more likely to be harmed by screening than he is to be saved by screening at nine years after diagnosis,” Drs. Brawley and Boyle noted.
You can read more in my other blogs on this topic:
- An influential doctors group is backing off its call for annual prostate cancer tests
- Routine Prostate Cancer Screenings Don’t Significantly Prevent Deaths, Research Shows