The pros and cons of “screening” for prostate cancer


A newly published article by Shoag et al. in the New England Journal of Medicine (NEJM) has suggested that the risks associated with “screening” for prostate cancer using the PSA test may not be as high as previously suggested. Specifically, the NEJM states that:

Shoag and colleagues review the long-term results of PSA screening from randomized trials and raise questions about whether the risk–benefit ratio is as strongly in favor of risk over benefit as currently gauged. The decline in PSA screening appears to have been precipitated in part by misinterpretations of data from randomized trials.

Unfortunately, the full text of this article is only available to subscribers to the NEJM. However, there is a summary of the article in yesterday’s issue of Renal and Urology News.

Based on that summary, it appears that Shoag et al. are arguing that a 25-year extrapolation of findings from the 16-year follow-up data from the European Randomized Study of Screening for Prostate Cancer (ERSPC) leads them to conclude that

  • 385 men would have to be screened and 11 additional cases of prostate cancer would need to be diagnosed to prevent one prostate cancer-specific death over a 25-year time span.

This compares to the data published by Hugosson et al. in 2019 based on the 16-year follow-up from the ERSCP, when the authors of that article stated that:

  • “The number of men needed to be invited for screening to prevent one PCa death was 570 at 16 yr compared with 742 at 13 yr. The number needed to diagnose was reduced to 18 from 26 at 13 yr.”

This is all very well, and no one (that your sitemaster is aware of) is disagreeing that the longer one goes on “screening” men for risk of prostate cancer, the greater the likelihood that one will (a) find some and (b) lower the potential risk for metastasis and death. However, there are a whole bunch of other issues that — in our view — remain very problematic.

First, as we have stated multiple times previously, the ERSCP was not a properly conducted, randomized screening trial. It was a meta-analysis of multiple screening trials at centers in multiple different countries across Europe, and it was conducted at a time when most of those countries have not previously been using the PSA test routinely to assess risk for prostate cancer.

Second,  the “screening” criteria and methodology in the ERSCP varied considerably from country to country, which turns the interpretation of all the data into a game of statistical methodology as opposed to clinical methodology, and (in case you have forgotten), if you make appropriate assumptions, you can use statistics to “prove” almost anything.

Third, Hugosson et al., in 2019, claimed that their finding of prevention of one prostate cancer death for each 570 men being screened at 16 years of follow-up was

qualitatively similar to recommendations supporting breast cancer screening, with the need to screen 1250 women from 50 to 59 years of age, and 769 women from 70 to 74 years of age to prevent one death from breast cancer at 10 years.

But there are actually a very large number of healthcare specialists who argue that we have been over-testing women for risk of breast cancer using mammography for decades too.

And then there is the whole question of what we mean by the use of the term “screening” anyway. Does this mean that every male over the age of 50 years should be getting a PSA test annually, or does it mean something much more like the “screening” protocol outlined by the group at the Memorial Sloan-Kettering Cancer Center, which is more like a form of selective PSA testing based on patient risk over time.

Finally, we would note that practically everyone disagreed with the US Preventive Services Task Force (USPSTF) recommendation from 2012 which recommended against any use of the PSA test to “screen” for risk of prostate cancer. That recommendation was reversed in 2018, and the current USPSTF recommendation is that a man between the ages of 55 and 69 should discuss the pros and cons of screening for risk of prostate cancer with the PSA test with his doctors based on his individual situation and perspectives.

We wish to be extremely clear about certain things in any discussion of  the controversial and contentious issue of “screening” for risk of prostate cancer:

  • There are several different groups of men who are clearly at higher than average risk for the development of clinically significant prostate cancer — based primarily on their germline genetic profile, family history, and race. These men would be wise, and should be encouraged, to consider careful use of appropriate tests to assess their risk for prostate cancer. Their risk is significantly higher than the average.
  • It remains true that a very large number of men can be found to have evidence of prostate cancer on autopsy at the time of their deaths even though they never had any signs or symptoms of this condition. Do we need to find these clinically insignificant forms of prostate cancer? Arguably, no, we  don’t. And the PSA test cannot be used with any degree of accuracy to find such prostate cancers anyway. It can only be used to necessitate further tests, which may also be unnecessary and come with significant risks.
  • The risk for side effects and complications from prostate biopsy remains significant — most particularly the risk from infectious complications of the procedure. Biopsies of all types are surgical procedures that come with varying levels of risk.
  • Access to pre-biopsy MRI scans that can be helpful in determining the need for a prostate biopsy — and how such a biopsy should be conducted — is extremely limited. Most men do not get and do not have insurance coverage for such pre-biopsy scans.
  • The services available through the types of specialized, academic cancer centers that are able to offer some of the newer, sophisticated services that can be used to minimize the risk for over-diagnosis and over-treatment of prostate cancer are simply not easily accessible to the majority of men in America today.
  • We believe that regular testing of some men of 70 years and older, who have a minimum life expectancy of a further 15 years, and who appear to be at some degree of future risk for clinically significant prostate cancer, is appropriate. Many, if not most, men of 70+ years of age do not, however, meet these criteria.

Prostate Cancer International’s fundamental position remains the same as it has for years now. We do not have a cost-effective and sufficiently accurate, high-quality test for risk for clinically significant prostate cancer that would be likely to lead to metastasis and death of the patient within (say) a 15- to 20-year time frame. The PSA test doesn’t come close to meeting that set of criteria. And no other test — e.g., tests like the Prostate Health Index or phi test and the 4KScore test — has ever been evaluated in clinical trials to assess such risk. Until we are able to find such a test and establish its accuracy and utility with a high degree of certainty, Prostate Cancer International believes, very sincerely, that use of the PSA test to assess risk for prostate cancer is the individual decision of each particular male in America.

We do not criticize those who want to have such tests. We do not criticize those who have decided not to have such tests. We encourage every man to develop a clear understanding of any and all factors (genetics, family history, race, etc.) that could significantly impact his individual risk for clinically significant prostate cancer and come to his own conclusions, in discussion with his doctors, about whether regular PSA testing is appropriate for him. And we are highly supportive of the “screening” protocol outlined by MSKCC as a methodology for helping the “average man in the street” to determine whether he is at clinically significant risk for prostate cancer over time.

The thing that we are absolutely opposed to is the idea that annual mass “screening” of the entire male population over (say) 45 or 50 years of age and up to (say) 75 years of age is a good idea. Bluntly, it isn’t. It would continue to lead to the now nearly 35-year history of over-diagnosis and over-treatment of clinically insignificant prostate cancer, along with all the complications and side effects of such over-diagnosis and over-treatment.

 

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