Researchers knew more information was needed when they saw the false-positive rate of the Veterans Health Administration lung cancer screening (LCS) demonstration project (58.2 percent) was considerably higher than the false-positive rate of the National Lung Screening Trial (26.3 percent).

The team worked to put these conflicting numbers into context, publishing its findings in JAMA Internal Medicine.

Examining LCS data from March 31 to June 30, 2015, and using the Bach risk model to assess lung cancer (LC) risk in the population, the authors separated patients into risk quintiles. They then reviewed the number of lung cancer cases, screening effectiveness and screening efficiency of each group.

Patients in higher quintiles of lung cancer risk had more lung cancer diagnoses. Initial screens were least effective and least efficient in those patients with the lowest risk. Initial screens were most effective and most efficient for patients with the highest lung cancer risk.

“We reexamined these data and found that the high false-positive rate results in a more concerning harm-to-benefit ratio for those eligible persons at lower LC risk, but a much better harm-to-benefit ratio for high-risk patients,” wrote lead author Tanner J. Caverly, MD, MPH, with the VA Center for Clinical Management Research and University of Michigan Medical School in Ann Arbor, and colleagues. “We found that even given these very high false-positive rates, the overall balance of pros and cons among patients at high lung cancer risk still surpasses those of most established cancer screening programs.”

The authors added that their analysis did not include all potential harms of LCS, including over diagnosis and psychological effects from false-positive results. They also called for effectiveness studies to “confirm the extend to which the mortality benefit observed in the National Lung Screening Trial, a 20 percent reduction in lung cancer and a 6.7 percent reduction in all-cause mortality, applies in actual practice.”

“These real-world findings reinforce the need to risk-stratify patients for LCS and provide support for personalized, risk-based harm-benefit estimates for all eligible persons during LCS decision-making,” the authors concluded.