Study Shows Significant Incidental Findings in Nearly 34 Percent of Lung Screening CT Exams

Significant incidental findings (SIFs) occur in approximately one-third of people who undergo lung screening with low-dose computed tomography (LDCT), according to newly published research.

For the retrospective study, recently published in JAMA Internal Medicine, researchers reviewed data from 75,126 LDCT exams for 26,455 participants (mean age of 61.4) in the National Lung Screening Trial (NLST), which was conducted at 33 academic medical centers in the United States between 2002 to 2009. According to the study, participant criteria for inclusion in the NLST included an age range between 55 to 74 and a 30-pack year history for current smokers or former smokers who had quit smoking within a 15-year period prior to the study.

Low-dose computed tomography lung screening revealed SIFs for 8,954 participants (33.8 percent), according to the study authors. The researchers also found that 89.1 percent of LCDT exams that led to SIF detection had reportable SIFs and there was over a 12 percent higher incidence of reportable SIFs for study participants with positive screens for lung cancer (94.1 percent) in comparison to those who had negative LCDT screens (81.8 percent).

At the initial LDCT screening, researchers noted that participants with a positive screen for lung cancer had a 30 percent higher incidence of SIFs over those with negative screens (44.1 percent vs. 14.1 percent). The study authors pointed out that emphysema was detected in 8,677 LCDT screenings.

“We reported that more than 10% of all LCDT screens showed signs of emphysema and/or chronic obstructive pulmonary disease (COPD). Early detection of these conditions may offer an opportunity for effective early intervention, including smoking cessation among those currently smoking, potentially reducing respiratory morbidity in these participants,” wrote study co-author Caroline Chiles, M.D., a professor of diagnostic radiology at the Wake Forest University Baptist Medical Center in Winston-Salem, N.C., and colleagues.

(Editor’s note: For related content, see “Emerging AI Tool Improves Worklist Triage and CT Detection of Incidental Pulmonary Embolism,” “Seven Takeaways from Best Practice Recommendations for Incidental Radiology Findings in the ER” and “Nine Takeaways from Recent Meta-Analysis on Lung Cancer Screening with Low-Dose CT.”)

In addition to emphysema, COPD, and lung hyperinflation accounting for 43 percent of reported SIFs in the study, the researchers noted that 12.1 percent were coronary artery calcification, 4.5 percent were unspecified but significant cardiovascular abnormalities and 3.2 percent were kidney masses.

“Optimal classification and reporting of SIFs, together with a tailored response to these abnormalities, can potentially minimize the unnecessary burden and costs borne by patients and (referring clinicians) and avoid iatrogenic morbidity and medically inappropriate care. Building on the classification of SIFs presented in this article may improve SIF management,” maintained Chiles and colleagues.

In regard to study limitations, the researchers noted they were unable to categorize 16.6 percent of the free-text comments accompanying the documented abnormalities on LDCT screens due to data-entry errors and a lack of specificity in some cases.