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Model suggests liquid biopsy improves prostate cancer outcomes, but that’s not the real world

"Liquid biopsy" test improves health outcomes and can save over $500 million annually for the U.S. healthcare system

Our Review Summary

Many cases of prostate cancer would benefit from a wait-and-see approach, but the available diagnostic instrument, PSA testing, leads to hundreds of thousands of prostate biopsies each year and, for some 18% of those tested, complications such as infections and sexual dysfunction arise. This news release describes a recent modeling exercise of the impacts of a non-invasive urine test, SelectMDx, that is already being used to identify cancers serious enough to warrant a full biopsy.  The exercise found that the test was of modest value to individual patients, leading on average to fewer than 20 additional healthy days, but could lead to significant societal cost savings over the course of a year for more than 300,000 patients by reducing the number of cases that move on to a full biopsy.


Why This Matters

Prostate cancer was the leading solid tumor and second leading cause of death from cancer in American males in 2017. Paradoxically, it also can simmer at a low ebb without medical intervention or harm for many men.  Figuring out whose cancer can be left alone and whose deserve a full-on attack has proved challenging, making the development of non-invasive screening tests important.  SelectMDx is one of several such tests.

All screening tests are non-invasive, the issue is that PSA is elevated not only in men without cancers but in men with low-risk cancers.  Making biopsy decisions based on PSA alone leads to unnecessary biopsies in men without cancer and often to unnecessary treatment in men with a low-risk cancer who undergo active treatment.


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

Not Satisfactory

Although a major aim of the study was to examine societal costs of employing this test, the actual cost of the test to an individual patient is nowhere to be found.  It appears to be in the hundreds of dollars, and there is no sign that Medicare is covering it as of yet.  The release notes that a number of US-based insurance companies have contracted to use the test.

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


The release does a good job of explaining the benefits of the SelectMDx test at both individual and societal levels.  Those benefits are pretty modest for a patient: a gain of 16 days of health at a cost savings of nearly $1700, on average.  But they are impressive when one ramps up to a societal level, given that more than 300,000 patients a year consider undergoing biopsies.

But it needs to be recognize that benefits and cost savings are estimated. The authors acknowledged that literature estimates for clinical benefits may not be applicable for the general population and the actual cost savings are uncertain because commercial payment rates are unknown.


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

Not Satisfactory

Although providing urine for the test involves little to no risk, choosing not to move forward with a biopsy as a result of the test does bring with it a risk of being wrong, should the cancer be aggressive (a false negative). The likelihood of that error would be an important piece of information.

The study cites a reference suggesting that the sensitivity for detecting high-risk cancers was 95.7%.

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

Not Satisfactory

The researchers appear to have built a mathematical decision model to simulate survival and cost outcomes of two conditions: a prostate diagnosis aided by a traditional biopsy or, alternatively, the initial employment of the SelectMDx test to judge if a biopsy is recommended. The news release offers little in the way of explanation.

The release seems to gloss over the fact this is a modeling study. The author’s quote that the study demonstrated that using the test improves health outcomes and lowers healthcare costs is misleading. The modeling results only suggest that it might.  We don’t know how the test would be applied or interpreted in real-world decision making so any actual benefits remain speculative.

Does the news release commit disease-mongering?


The release doesn’t engage in disease mongering. It provides helpful context on the numbers of prostate cancer diagnosed each year, as well as the complications associated with testing and followup treatment. Given the relatively high rate of complications stemming from the many prostate biopsies that are conducted each year, this effort to validate a non-invasive diagnostic test could have value.

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

Not Satisfactory

Neither element shows up in the text.  Since the news release comes from the company MDxHealth, which is marketing the test, one might assume that the company paid for the study.  But the text of the research report suggests otherwise, indicating funding from the American Cancer Society and a foundation focused on urological research. That would have been a useful addition to the release.

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

Not Satisfactory

Although the text does a good job of explaining the risks of a prostate biopsy, it does not make clear that the gains found in the study stem from a comparison of employing the SelectMDx test to determine if a particular prostate cancer warrants further diagnostic efforts versus using a PSA test or ultrasound to make such a judgment.

The traditional alternative is actually to make biopsy decisions based on PSA alone–not ultrasound (which is used for the biopsy).  However, MRI is increasingly being used to identify potential high-risk tumors and guide guide biopsy decisions: MRI-targeted or standard biopsy for prostate-cancer diagnosis.  Kasivsisvanathan V, et al. N Engl J Med 2018; 378:1767.

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

Not Satisfactory

The lead correctly identifies the research as a “new” study but fails to acknowledge the publication of a very similar piece of research more than a year earlier that generated almost identical results in Europe.

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


Much of the release focuses, appropriately, on the cost-effectiveness of the test at an aggregate level.

Total Score: 4 of 10 Satisfactory


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