While the National Lung Screening Trial (NLST) provided a wealth of evidence on the effect of low-dose CT (LDCT) screening on lung cancer mortality, it remains to be seen how that information will—or should—be used, according to a teleconference discussion of the benefits and harms of CT screening for lung cancer organized by the Institute for Healthcare Improvement and the Journal of the American Medical Association (JAMA).

The discussion featured Peter B. Bach, MD, of Memorial Sloan-Kettering Cancer Center in New York City, who was the lead author of a systematic review of LDCT lung cancer screening evidence published in JAMA, and George T. O’Connor, MD, of Boston University School of Medicine, who wrote an accompanying editorial.

Bach began by summarizing the review of evidence. He and colleagues reviewed 21 studies, three of which were found to provide evidence on the effect of LDCT screening on lung cancer mortality. The largest by far was the NLST, which demonstrated a 0.33 percent absolute decrease in lung cancer death. This equates to three lung cancer deaths avoided per 1,000 screened, explained Bach.

The findings of the review formed the basis of a clinical practice guideline issued by the American College of Chest Physicians (ACCP) and the American Society of Clinical Oncology (ASCO) which said annual screening with LDCT should be offered to smokers and former smokers, age 55 to 74, who have smoked for 30 pack years or more.

O’Connor noted, however, that the wording of the recommendation leaves a little to be desired. By recommending that screening should be offered—and not saying it should be done or become the standard—the decision is left up to the patient and his or her physician.

“That’s a little vexing in clinical practice,” said O’Connor. Bach echoed this concern, saying it’s undesirable to foist such a difficult decision on patients and their doctors without laying our more clear-cut recommendations.

Bach also stressed that the review did not look at the cost-effectiveness of LDCT lung cancer screening because there was no published evidence using primary data, though he said a cost-effectiveness analysis featuring NLST data is in the works. Coverage decisions in the U.S. are typically not made based on cost-effectiveness, said Bach, and while Medicare could decide not to cover LDCT screening even if it’s endorsed by the U.S. Preventive Services Task Force (USPSTF), they have never made such a decision in the past.

As to whether USPSTF will support the ACCP/ASCO recommendation—or make a similar recommendation slightly more tailored to certain populations—Bach refused to hazard a guess, though he said a final decision by USPSTF is expected in fall 2013.