The U.S. Preventive Services Task Force recently released a new recommendation on screening for lung cancer.
The USPSTF recommends annual screening for lung cancer with low-dose computed tomography in adults ages 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.
We often see imbalance in news coverage about screening tests. It often happens when evidence-based guidelines recommend against some form of screening or when they raise questions about the tradeoffs between benefits and harms. In such cases, many news stories seem to take an almost advocacy stance promoting mass screening, with no discussion of concerns over the tradeoffs involved. But this was a guideline that made a very clear recommendation for screening (albeit in specific circumstances).
And still, a major news source – NBC News – exaggerated the potential benefits while ignoring the issue of potential harms.
The anchor lead-in by Lester Holt said that the screening could save "tens of thousands of lives" each year. This clip from the NBC story demonstrates how NBC News chief medical editor Dr. Nancy Snyderman allowed Dr. Claudia Henschke to claim that "the new guidelines could save more than 30,000 lives a year." (You'll need to listen to an NBC promo first before you get to the edited news segment.)
And, as you just saw, the story featured the predictable positive anecdote, one which will not be representative of all patients' experiences. But this was clearly not a story framed to discuss unsatisfactory experiences. This was about saving "tens of thousands" or "more than 30,000″ lives a year.
Let's look closer at those claims.
In the journal Cancer just nine months ago, American Cancer Society researchers estimated the "annual number of lung cancer deaths potentially avertable by screening in the United States." The most relevant excerpt:
"If the uptake rate is 70 percent, which is approximately the prevalence rate of mammography screening during the past two years among US women aged ≥ 50 years in 2010, approximately 8,600 lung cancer deaths would be averted annually by low-dose computed tomography screening performed within the United States."
8,600 lives a year.
An order of magnitude short of the "tens of thousands" or "more than 30,000″ per year projected by NBC and its single, conflicted source.
Meantime, the NBC story didn't have a word about potential harms of lung cancer CT screening. The USPSTF report, on which their story was based, talked a lot about potential harms. Excerpts:
Because of the low positive predictive value of screening low-dose computed tomography (LDCT), subsequent procedures are often needed for diagnosis. These procedures are usually noninvasive, such as clinical examinations, repeated CT, and positron emission tomography; however, some may be invasive, such as biopsy and surgery... (There is a) high number of false-positive findings requiring further evaluation with imaging or clinical follow-up, which were predominantly done for benign disease.
Overdiagnosis and consequent overtreatment is a concern in lung cancer screening. The 1 percent to 2.7 percent prevalence of unrecognized lung cancer suggests a preclinical pool of lung cancer in high-risk populations. The clinical significance of these tumors is uncertain, but patients with lung cancer typically receive treatment, resulting in harm to those with nonlethal cancer. Elderly smokers have high mortality rates from causes other than lung cancer, which also increases the risk for overdiagnosis.
Radiation exposure is a harm of LDCT lung cancer screening. For context, LDCT is associated with radiation exposure near that of mammography. Radiation-induced cancer over 10 to 20 years is particularly concerning, although none of the studies reported on this potential outcome.... If LDCT screening becomes routine, it will be important to measure the risk for radiation-associated harms and identify methods to lower the dose.
When we talk about a consistently clear pattern of news stories about screening tests that exaggerate or emphasize benefits while minimizing or ignoring harms, we are talking about stories exactly like this one.
This post originally appeared on Gary's Health News Review blog on January 6, 2014.