Detecting breast cancer from tears? Facebook video news story is just long enough to mislead

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Kevin Lomangino is the managing editor of He tweets as @Klomangino.

We’ve all seen those captioned Facebook videos designed to grab distractible feed-scrollers by the eyeballs and compel them to pay attention.

They’re great for sharing stories like this one about a dog and a kitten who’ve become “friends fur life.”

They’re also apparently quite effective for delivering political responses to the latest happenings in the presidential campaign.

But when it comes to news about a topic as complicated and as personal as breast cancer screening, a recent video from Al Jazeera English, the Qatar-based international news channel, shows that these videos also have the potential to deliver simplistic and misleading messages on issues that demand greater depth and clarity.

Clocking in at a tight 41 seconds, the video is just long enough to make some advertising-like claims about the benefits of a cheap experimental test that supposedly screens for breast cancer using a person’s tears.

But those claims don’t provide any useful or meaningful information about the test’s capabilities or its role in the detection of breast cancer, said Saurabh Jha, MBBS, Assistant Professor of Radiology at the University of Pennsylvania and a contributor.

He pointed specifically to the claim that the test is “twice as accurate” as a mammogram.

“Accuracy” is a meaningless term in screening. You can be > 95 % accurate if you call all mammograms “negative for cancer.” So how a test claims to be “twice as accurate” baffles me. What you need to know with this test is how many false negatives (it said “no cancer” when there actually was cancer present) and false positives (it said “cancer” when there actually was no cancer) it generates in a thousand women who are screened for breast cancer. There will always be a trade-off between false positives and false negatives.

In other words, the more cancer that a screening test finds, the more likely that it will also provoke more false alarms that turn out not to be cancer. A test that provokes fewer false alarms is similarly prone to missing more cases of real cancer.

You simply can’t judge a test’s value in screening if you aren’t given both sides of that equation.

Breast surgeon Deanna Attai, MD, also a contributor as well as an Assistant Clinical Professor of Surgery at UCLA, highlighted another problem that’s not addressed by the video:

The video seems to suggest the value might be in detecting cancer in areas where traditional screening techniques are not available, but of course no one is addressing the issue of overdiagnosis. Does this test detect clinically significant cancers? The video states that it will tell you if “cancer is present in your body or not” – does it tell you what type of cancer? Is it specific to breast cancer? If not, there will then be a whole slew of diagnostic tests trying to find out where the lesion is.

Overdiagnosis — finding cancer that’s so slow-growing that it would never progress to cause problems — is a well recognized concern with many forms of cancer screening, including for breast cancer. It’s particularly worrisome when dealing with ductal carcinoma in situ (DCIS) — sometimes referred to, misleadingly, as “stage 0 breast cancer.”

Simply finding more cancer isn’t a solution if we can’t distinguish between cancer that needs to be treated and that which can be safely monitored.

Some Facebook commenters on the video, which has been viewed more than seven million times as of this writing, raised these and other issues that Al Jazeera would have done well to address:

It’s heartening to see so many viewers thinking critically about this video’s message and pushing back against its unsubstantiated claims.

But how many women — like this one — will be confused and misled into thinking that this test is a cheap alternative to mammograms that might be available to patients right now?

That number may not be knowable but it’s certainly one worth thinking about.

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