Evidence Lacking to Support or Oppose Low-dose CT Screening for Lung Cancer, Says AAFP

Inability to Make Harms/Benefits Comparison Precludes Definitive Recommendation

January 13, 2014 04:50 pm Cindy Borgmeyer

Citing a paucity of high-quality evidence on which to base a comparison of relative harms and benefits, the AAFP today released an "I" recommendation regarding the routine use of low-dose CT scans in screening high-risk, older smokers for lung cancer.

[Stock photo-Close up of man smoking cigarette]

The Academy's action puts it at odds with a recommendation issued last month(www.uspreventiveservicestaskforce.org) by the U.S. Preventive Services Task Force (USPSTF).

Specifically, the new AAFP recommendation states: "The AAFP concludes that the evidence is insufficient to recommend for or against screening for lung cancer with low-dose computed tomography (LDCT) in persons at high risk for lung cancer based on age and smoking history."

The USPSTF, on the other hand, "recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years."

Story highlights
  • The AAFP has said the evidence is insufficient to recommend for or against screening for lung cancer with low-dose CT in people at high risk for lung cancer based on age and smoking history.
  • The Academy's action puts it at odds with a recommendation issued last month by the U.S. Preventive Services Task Force.
  • It's important for physicians to engage in shared decision-making with patients regarding the benefits and potential harms of screening for lung cancer.

"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," the task force recommendation concluded. The recommendation received a "B" grade, meaning that, in accordance with the Patient Protection and Affordable Care Act, it eventually will become a covered health benefit with no patient cost-sharing.

Interpreting the Evidence

In the clinical considerations section of its recommendation statement, the Academy noted that it had "reviewed the USPSTF's recommendation on lung cancer screening and had significant concern with basing such a far reaching and costly recommendation on a single study." That study, the National Lung Screening Trial(www.ncbi.nlm.nih.gov) (NLST), was conducted exclusively in major U.S. medical centers with strict follow-up protocols for nodules identified. The favorable results seen in the NLST have not been replicated in a community setting.

According to Doug Campos-Outcalt, M.D., M.P.A., of Phoenix, the AAFP liaison to the USPSTF, "There actually were four studies; the one that was done in the United States is the largest and showed the most benefit." The other three trials, he noted, were conducted in Europe and were not considered to be of the same quality as the NLST, which was a randomized controlled trial that involved more than 50,000 participants. Moreover, the European studies failed to show the same magnitude of benefit seen in the NLST.

"Usually, what you do when you try to answer a question like that is you compile the studies into a meta-analysis, said Campos-Outcalt, who also serves as clinical methodologist to the AAFP's Commission on the Health of the Public and Science, which assessed the USPSTF recommendation. In this case, he added, "when you do that, the benefits of this (screening) are not as striking."

"The other issue," said Campos-Outcalt, "is that even that (NLST) study only scanned people three times -- they did annual scanning three times." Thus, the USPSTF had to rely on modeling based on a number of assumptions to make its harms/benefits determination.

Moreover, Campos-Outcalt continued, "the task force is actually recommending annual screening for as long as you meet the criteria. If you're a smoker, that may mean annual scanning from age 55 to 80."

The risks attendant in such a long-range screening protocol cannot be ignored, Campos-Outcalt contended. To achieve the roughly 20 percent relative reduction in mortality estimated by the NLST, "there's going to be a considerable amount of testing that's going to be required, including some biopsies and some bronchoscopies and some other procedures that have risk to them," he said. "So this is not going to eliminate all the risks, and 80 percent of the mortality from lung cancer is still going to occur."

Given that more than 300 people would have to be annually screened at least three times during a five-year period to save one life -- and given the unknown harms in this being applied community-wide -- "the AAFP felt that it was not possible to do a harms/benefits analysis," Campos-Outcalt noted.

In addition, he said, "It's going to be real important not to be aggressive in following up on questionable findings. Most of these centers (in the NLST) waited and then rescanned before jumping right into invasive procedures. That's where you're going to get more harms: being aggressive in following up on questionable findings."

Talking With Patients

According to the AAFP recommendation statement, "A shared-decision-making discussion between the clinician and patient should occur regarding the benefits and potential harms of screening for lung cancer." During that discussion, Campos-Outcalt suggested it may be helpful to point out to patients that although the annual CT screening scans for high-risk smokers would be covered with no copays or other cost-sharing, any follow-up testing performed would not.

"So if patients have to have a follow-up CT scan, a follow-up biopsy, a follow-up consultation -- those services will come with deductibles and copays." Patients also would bear the cost of such often overlooked factors as travel to obtain the screening, as well as to complete any follow-up testing indicated. "That's not a risk-free activity, either," Campos-Outcalt observed.

"So although it may come across as a no-brainer -- the screening saves lives, it's free and so forth -- it's just not that simple," he explained.

"People need to understand that their life expectancy could be extended by this," said Campos-Outcalt, "but on the other hand, their life expectancy could be shortened by it."

Perhaps most important when talking with these high-risk patients, he advised: Don't forget to address the elephant in the room.

"If they're currently smoking, a better thing to do by far is to stop smoking. This is not a substitute for stopping smoking."

Related ANN Coverage
USPSTF Gets Behind Screening for Lung Cancer
Annual Low-dose CT Scans Now Recommended for High-risk Adults


Additional Resources
U.S. Preventive Services Task Force Fact Sheet: "Talking With Your Patients About Screening for Lung Cancer"(www.uspreventiveservicestaskforce.org)

Choosing Wisely: American College of Chest Physicians and American Thoracic Society Recommendation No. 5(www.choosingwisely.org)