Standardized SIF Reporting, Management Guidelines Needed in LDCT Lung Screening

Significant incidental findings (SIFs) were common among patients undergoing low-dose computed tomography (LCDT) lung cancer screening in the National Lung Screening Trial (NLST), and many SIFs were reportable for follow up in a retrospective case series study published in JAMA Internal Medicine.

The findings suggest that standardized guidelines for SIF reporting and management following LDCT lung cancer screening could help optimize the treatment of patients whose LDCT scans show SIFs.

“At LDCT screening, potentially significant abnormalities not associated with lung cancer, commonly referred to as SIFs, are often detected,” wrote the researchers of the study. “These findings have potential clinical significance and are sufficiently concerning to the interpreting radiologist that they are reported to the referring clinician (RC).”

Researchers aimed to better understand the importance of SIFs seen in LDCT lung screenings and explore the nature of those SIFs.

The study used data from the NLST, which aimed to determine whether LDCT is associated with lung cancer mortality reduction vs chest radiography. The NLST included a total of 53,452 participants aged 55 to 74 years with at least a 30 pack-year cigarette smoking history who were either current smokers or former smokers who quit within the previous 15 years. The LDCT arm of the NLST included 26,722 individuals from 33 different academic centers in the United States from 2002 to 2009.

Eligible patients for the current study had to have undergone at least 1 screening examination with LDCT, resulting in a total of 26,455 participants after exclusion. The lung screenings were interpreted and classified as positive (suspicious for lung cancer) or negative (no findings suggestive of lung cancer).

Individuals with a negative lung cancer screening result were grouped as either negative screen with significant abnormalities not suspicious for lung cancer (NEG/SIF) or negative screen with no significant abnormalities (NEG). Individuals with positive lung cancer screening results may also have had SIFs detected and were grouped as positive screen with significant abnormalities (POS/SIF).

SIFs reported among participants for lung cancer were identified as: emphysema, a significant cardiovascular activity, other potentially significant abnormality above diaphragm, and other potentially significant abnormality below diaphragm.

Of the total eligible participants who underwent screening, 10,833 (41.0%) were women and the mean (SD) age was 61.4 (5.0) years. Additionally, 24,123 (91.2%) were White, 1179 (4.5%) were Black, and 470 (1.8%) were Hispanic/Latino.

After screening, 8954 (33.8%) SIFs were reported. Among all screening tests with a SIF detected, 12,228 (89.1%) had a SIF that was deemed reportable. Additionally, a higher proportion of SIFs considered reportable were among those with a positive screen for lung cancer (7632 [94.1]) compared with individuals who had a negative screen result (4596 [81.1%]).

The most common of the 20,156 SIFS reported were:

• Emphysema, 8677 (43.0%)
• Coronary artery calcium, 2432 (12.1%)
• Masses or suspicious lesions, 1493 (7.4%), including masses in the kidney liver, adrenal, and breast

However, the study had limitations. It was unable to categorize 2205 of the 13,299 (19.6%) free text comments used for classification, mostly because of data entry errors on lung abnormalities associated with lung cancer rather than a SIF. Additionally, some comments were not specific enough to be classified for a screening recommendation.

Despite limitations, the researchers believe this study serves as a template for identifying important SIFs, and advocates for further research to be done to better understand the association between these SIF with morbidity and mortality, as well as implement these screenings into the real world. Future screening trials should standardize the reporting of SIFs, the authors noted.

“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 RCs and avoid iatrogenic morbidity and medically inappropriate care,” wrote the researchers. “Building on the classification of SIFs presented in this article may improve SIF management.”

Reference

Gareen IF, Gutman R, Sicks J, et al. Significant incidental findings in the National Lung Screening Trial. JAMA Internal Medicine. 2023;183(7):677. doi:10.1001/jamainternmed.2023.1116