The bottom line is that the value of the new test remains quite uncertain. The study’s sample size was small, the follow-up period appeared relatively short, and the accuracy statistics were difficult to interpret. The story reports on a study in 71 men, but allows another source to throw in unsourced information about a Chicago-area study in 2,000 men.
It seems quite unlikely that – as the story states – "it will take another year or two to get enough cases to nail down the predictive value" with sufficient precision or validity to change practice. . And to tell readers that it’s already approved in Europe without providing any information on the European experience with it is not helpful.
There is no discussion of costs for this product.
While it is currently not approved for clinical use in the US, the story could have extrapolated from princing in Europe. Would it be expected to double screening costs or inflate them by a factor of 10?
The story didn’t provide quantitative data on potential benefit. The story indicated the test might help identify men who could delay or defer treatment of their prostate cancer, but it did not provide any estimate of the proportion of men that might be expected to reap this benefit.
The story also mentioned in passing an additional benefit which was that the test might reduce the frequency of prostate biopsies from every year to every other year. However it should be noted that current guidelines for the frequency of follow-up biopsies are variable and some recommend intervals of up to at least 18 to 24 months – which would mean this test would result in no change.
The story did not provide insight about the individuals who were incorrectly diagnosed in the study reported on. What percentage of men had aggressive tumors that the test failed to detect? And what percentage of men received treatment because the test identified them as having aggressive tumors but actually did not need to be treated?
The story reported that the test was 70% accurate in "singling out aggressive tumors" and that the data reported on were from a small study and finally that the results reported on had been described at a recent meeting. However the story never linked these three pieces of information together to provide a clear statement indicating that this information is preliminary.
What does it mean that the test is 70% accurate? Does it correctly identify aggressive tumors 70% of the time and that 30% of the time aggressive tumors go undetected? Or does it mean that of the tumors suggested to be aggressive, really only 70% are and the remaining 30% of men receive treatment for something that didn’t need to be treated? The story did not include enough information to know. More useful statistics in describing diagnostic tests are sensitivity–in this case the proportion of men with progressive cancer who tested positive–or specificity–the proportion of men whose cancer did not progress and who tested negative.
If this test is used in Europe, surely that use is not based on the results of the current study. Therefore the story should have included some insight about other work indicating the value of this test.
Lastly – reporting about results presented at a meeting means that these results have not been vetted by experts. The story should have indicated this.
The story did not engage in disease mongering.
Instead of suggesting in the first sentence that this test might help identify those prostate cancers that did not require immediate treatment, the story could have stated that it might identify those prostate cancers that might never require treatment.
The experts quoted in the story appear to have an association with Beckman Coulter, Inc, the company planning to market the test reported on. This was not made clear in the story.
The existing alternative is to use the PSA test, digital exam, and biopsy results to determine whether a man should consider aggressive treatment. The story does not indicate how much more accurate the new test was compared to PSA. The glib comment about a coin flip does not necessarily accurately characterize the study results.
Perhaps the story also should have told readers that there are other companies with similar sorts of tests in development.
The story mentioned that this test is currently "awaiting" FDA approval for use in the US but has already been approved for use in Europe.
This type of wording is misleading because it may imply that FDA approval is a done deal. It would be better reporting to state that the product is being considered by the FDA for approval.
It is not clear from the story what the actual components of the Prostate Health Index and the DNA content measures were. The story did not detail whether the individuals tests are being combined in a new way or whether some were new.
It does not appear that the story relied solely on a news release.