Stories about Elizabeth Edwards’ breast cancer and Tony Snow’s colon cancer have led some news organizations to offer recommendations about cancer screening. Unfortunately, some of the recommendations are simply not based on evidence.
On the NBC Today show on March 28, Matt Lauer said the Edwards and Snow cases put “a huge spotlight on the importance of early detection.” Did they? The Edwards and Snow cases were not about early detection; they were recurrences. Theirs were not stories about cancer screening in the general population of people without symptoms. They were stories about follow up testing and recurrence in people who already had been treated for cancer. That’s an important distinction, glossed over in the kind of introduction Lauer used.
And to use the Edwards and Snow cases to stir up enthusiasm for early detection in ways that fall outside the boundaries of the best evidence is troubling.
Lauer brought on NBC News chief medical editor Dr. Nancy Snyderman and the two of them reviewed recommendations for screening tests for breast cancer, colon cancer, lung cancer and prostate cancer. But the discussion weaved in and out of the boundaries of evidence.
In discussing colon cancer screening, Snyderman explained that because she has a family history, she started having colonoscopies at age 40 in two to three year intervals. She says now that she’s over 50 she gets one every year. “And I get one more than my doctors really recommend because I just get a little nervous about it,” Snyderman said.
It’s fine for her to choose whatever path makes sense to her. But it is troublesome to use a national TV platform to leave even the perception that this is an evidence-based course. The frequency of her screening is far more aggressive than the intervals described by the U.S. Preventive Services Task force for most people in the viewing audience.
Annual FOBT (fecal occult blood testing) offers greater reductions in mortality rates than biennial screening but produces more false-positive results. A 10-year interval has been recommended for colonoscopy on the basis of evidence regarding the natural history of adenomatous polyps. Shorter intervals (5 years) have been recommended for flexible sigmoidoscopy and double-contrast barium enema because of their lower sensitivity, but there is no direct evidence with which to determine the optimal interval for tests other than FOBT. Case-control studies have suggested that sigmoidoscopy every 10 years may be as effective as sigmoidoscopy performed at shorter intervals.
Snyderman wrote off the value of sigmoidoscopy, saying it doesn’t go far enough (her words), and said that viewers must have colonoscopy.
But the U.S. Preventive Services Task Force recommendation says:
It is unclear whether the increased accuracy of colonoscopy compared with alternative screening methods (for example, the identification of lesions that FOBT and flexible sigmoidoscopy would not detect) offsets the procedure’s additional complications, inconvenience, and costs.
Next, Snyderman turned her pro-screening enthusiasm to prostate cancer, advising men: “You turn 50, you just have to have a rectal exam to feel that prostate. And you get a prostate-specific antigen, a PSA test.”
Contrast that with the evidence-based guidelines:
The U.S. Preventive Services Task Force (USPSTF) concludes that the evidence is insufficient to recommend for or against routine screening for prostate cancer using prostate specific antigen (PSA) testing or digital rectal examination (DRE).
We have written about the one-sided, pro-screening enthusiasm exhibited on some network TV newscasts before.
Journalists should not be advocates, especially if their advocacy is based on personal opinion, not evidence or fact.
A good source for an evidence-based assessment of these issues: “Should I Be Tested For Cancer? Maybe Not and Here’s Why,” by H. Gilbert Welch, M.D., MPH. (University of California Press, ISBN 0-520-23976-8).