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Even casual readers expect more than broad claims about screening tests. Where’s the data?

Study: New blood test is more accurate in predicting prostate cancer risk than PSA

Our Review Summary

This Cleveland Clinic news release describes a “new” blood test called IsoPSA that is supposed to be more accurate than traditional prostate specific antigen (PSA) blood tests. Instead of determining PSA concentrations in the blood or other bodily fluids, IsoPSA recognizes the protein’s structural changes. Researchers believe this test could help distinguish prostate cancer from benign conditions and identify patients with high-grade disease.

It’s not exactly clear what’s new here, however. These types of structurally-based PSA tests have been around since 2009. The news release does a decent job cautioning readers on overdiagnosis and overtreatment after positive PSA tests. It also discloses conflicts of interest, as the principal investigator is a co-founder and chief medical officer of Cleveland Diagnostics — the biotech company that funded this study.

We wish we were given some numbers to put some of the claims into perspective. Benefit data were given in relative terms and described with vague, comparative wording. Also missing are discussions on the study design and limitations, as this study did not have a control group.

 

Why This Matters

PSA screening has been the subject of debate the past few years. In fact, many experts believe screenings may do more harm than good in the long run, especially since routine PSA screenings lead to over-diagnosis of harmless cancers. This then leads to treatments for prostate cancer, which come with higher risks for side effects.

One European study showed an additional 48 men who were not at risk of dying from prostate cancer had to be treated to prevent one death from the disease.

Another alternative to traditional PSA blood tests is certainly of public interest, especially if the test is comparable in cost while being more sensitive to aggressive prostate cancers.

Criteria

Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

There is no discussion of costs in this news release — neither the cost of the test or the potential savings if it decreases false positive results which lead to further testing or treatment.

A regular PSA test is typically covered by insurance, especially for men over the age of 50. According to Healthcare Bluebook, a PSA test should cost around $48 for patients without insurance, but prices may vary depending on location. This price also does not include the office visit.

We feel the news release should give consumers a ballpark estimate of costs, even if it is a new test. Therefore, we give the news release a Not Satisfactory rating here.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The news release uses vague, comparative language to describe the benefits of the new blood test, such as IsoPSA may “substantially reduce” the need for biopsy and IsoPSA proved “significantly superior” to PSA. Here, the word “significant” is ambiguous because it means “statistically significant,” instead of the colloquial meaning of the term.

In addition, IsoPSA could “significantly reduce the rate of unnecessary biopsies by almost 50 percent.” Instead of relative terms, we prefer benefit data to be written in absolute reduction risk to provide a more accurate impression of how effective the new test really is. Even if the journal article reports its results relatively, we still expect the writer to follow up with the researchers and provide some quantitative data for readers.

Basically, the study used the gold standard of the biopsy result to compare PSA (the current test) to IsoPSA (the new test). The study itself provides numbers for the sensitivity and specificity of these two tests to detect any cancer as well as to detect higher risk cancer. These numbers could have been provided and explained.

Without any raw numbers, it’s hard for us to judge whether IsoPSA is indeed more accurate than PSA. We give the news release a Not Satisfactory rating here.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

There are no great harms associated with taking a blood test, but we do know there are harms associated with screening tests. They can lead to false positives, additional tests and over-treatment of low risk prostate (and other cancers) that might never have caused harm. Patients may also suffer psychological effects if they are confronted with false positive test results. The side effects of treatment for these tumors can be serious — impotence, incontinence and bowel dysfunction. Though one could argue this new test may decrease those harms, it is unproven at this point.

We rate this one Not Satisfactory.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The news release does a good job cautioning readers on PSA screenings, since PSA is “tissue-specific but not cancer-specific, leading to over-diagnosis and over-treatment of biologically insignificant cancers.”

However, we aren’t given a lot of details on the study itself. All we know is that it was a multicenter prospective study with 261 men and that they were enrolled between August 2015 and December 2016 at five US centers. Participants were already scheduled for prostate biopsy.

We don’t know how these men were selected and how old they were. Furthermore, the news release doesn’t point out any study limitations, such as the lack of a control group. The journal article mentions there was no standardized pathology review of the biopsies, as well as no distinction between primary and repeat biopsies.

We would have liked more discussion on the study design and limitations, which is why we give the news release a Not Satisfactory rating here. 

Does the news release commit disease-mongering?

Satisfactory

There is no disease mongering in the news release.  It provides some useful context on the pros and cons of PSA screening.

Does the news release identify funding sources & disclose conflicts of interest?

Satisfactory

The IsoPSA test was developed by Cleveland Diagnostics, which also funded, designed and conducted the study. The principal investigator is a co-founder and chief medical officer of Cleveland Diagnostics and has investment interest in the company.

Since the news release disclosed these facts, we give it a Satisfactory rating here.

Does the news release compare the new approach with existing alternatives?

Satisfactory

The news release compares IsoPSA to the current PSA blood test. IsoPSA detects molecular changes in the protein, it states. According to the journal article, IsoPSA is a structure-based assay encompassing the entire spectrum of the protein’s structural changes.

Conventional tests are based on PSA concentrations in the blood or other bodily fluids.

Although the news release doesn’t go into much detail about current tests, we feel it does a good enough job for a Satisfactory rating here.

However, it would have been good for the release to highlight that the current test is not uniformly recommended. No testing is a reasonable option according to the USPSTF’s draft screening recommendations.

Does the news release establish the availability of the treatment/test/product/procedure?

Satisfactory

The news release makes it clear that IsoPSA is not available at your local doctor’s office, since this blood test needs to undergo further study and then be adopted clinically.

Does the news release establish the true novelty of the approach?

Not Satisfactory

It is clear that this release is about the search for a better test. It’s not exactly clear what’s new here, since having a structurally-based PSA test is not a novel idea. IsoPSA is also known as PSA/SIA (Solvent Interaction Analysis) — an assay that has been described in medical literature since at least 2009.

In a Journal of Urology article, researchers used the same technique to differentiate structural PSA forms in urine. In the study, the PSA/SIA assay had been developed by AnalizaDx, Inc., a Cleveland-based biotech company. Interestingly, the first author of this article is Mark Stovsky, the principal investigator of the current European Association of Urology article.

Since the news release doesn’t include this background information, we give it a Not Satisfactory rating. 

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Satisfactory

The news release does not include unjustifiable, sensational language.

Total Score: 5 of 10 Satisfactory

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