Prevention magazine confuses screening tests with diagnostic tests & why that's a problem

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4 screening tests women fear.jpgSome publications love lists.

Prevention magazine is one such publication.

The March issue is out and the first big story is “4 Screening Tests Women Fear.”

The problem is: only 2 of the 4 tests discussed are screening tests.

Yes, mammograms and colonoscopies are screening tests – used in an apparently healthy population looking for signs of trouble.

Endoscopies and MRI scans – as discussed by Prevention in this case – are not screening tests but diagnostic tests used to help diagnose what is the problem in people with signs or symptoms of something wrong. Screening tests are for people believed to be healthy. Diagnostic tests are for people believed to have a problem.

Prevention even writes: “Endoscopy is used to investigate the cause of specific symptoms.” That’s not screening.

They write about MRI: “Doctors use MRI to help diagnose everything from torn ligaments to brain tumors and cancer.” Diagnose, not screen.

The semantics are important. Lumping diagnostic tests like endoscopy and MRI in with screening tests like mammograms and colonoscopies can give readers the impression that everyone should consider all of them. And, no, not everyone needs to be worried about when to have their next endoscopy or MRI scan (even though the trendlines in our medical arms race would steer more and more of us toward these tests for some reason or another, justified or not.)

And even when the feature did discuss screening tests, its information was incomplete.

It cites a Swedish study that “found that regular mammograms can cut the death rate of women in their 40s by up to 29%.” I suggest that Prevention’s editors read my blog post, “This is the way the Swedish mammography study could/should have been analyzed.

As alternatives to colonoscopy, Prevention mentions virtual colonoscopy and virtually predicts FDA approval (as soon as 2012) for a DNA stool test. There was no mention of the fact that the U.S. Preventive Services concludes that the evidence is insufficient to assess the benefits and harms of either approach.

This “news you can use” light, fluffy feature list of “screening tests women fear” should ratchet up the right information and ratchet down the fear – for the sake of public health.

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Comments (4)

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Gregory D. Pawelski

February 19, 2011 at 11:25 am

The biological/clinical considerations are these: The efficacy of screening for breast cancer depends not only upon test accuracy, but upon the efficacy of proceeding with definitive diagnosis and therapy versus the efficacy of doing nothing at all. This is the problem with mammography for breast cancer.
There is no doubt that screening mammography can identify cancer at an earlier stage than in the absence of screening. But so what?
Biologically, it appears that many cancers diagnosed at an earlier stage with screening are so aggressive that, even at the time of the time of earliest possible detection, there are already micrometastases, meaning that earlier extirpation of the primary tumor does not influence ultimate outcomes in a meaningful way.
More commonly, tumors are so indolent that metastases would not have occurred, even had diagnosis been delayed by one, two, or several years (i.e. until the lesion became palpable and was diagnosed in the former, pre-screening manner).
So the only patients helped by screening are those who (1) are accurately detected by the screening exam and (2) which have a “Goldilocks” biology — not too aggressive/not too indolent. Balanced against this is the harm caused by screening, with respect to the false positives and the underlying morbidity of the screening procedure (e.g. chemo and/or radiation exposure).

Elaine Schattner, MD

February 22, 2011 at 10:01 am

Thanks for this post.
I agree that clear language helps patients understand what’s being said about preventive medicine and any form of cancer screening. What would be even better is if journalists could take this to the next level, and avoid lumping together all forms of cancer screening in one discussion about it being effective or not.