Structured reporting has revealed a distinct pattern of clinically significant incidental findings identified through lung cancer screening (LCS) low-dose chest CT scans (LDCT) that represent potential opportunities for early intervention for other health conditions, researchers have reported.
The findings not only validate the clinical utility of seven prespecified "S modifiers" that likely reflect shared risk factors or underlying disease processes but also suggest it is time to integrate LCS data with national mortality registries, according to a team led by Hyungjin Kim, MD, PhD, of Seoul National University College of Medicine in South Korea. The research was published January 6 in Radiology.
"As S modifiers encompass diverse disease processes, assessment of disease-specific mortality (e.g., respiratory, cardiovascular, or cancer-related deaths) would provide further insights into their prognostic value," Kim and colleagues wrote.
When the Republic of Korea implemented its population-based Korean National Lung Cancer Screening Program in 2019, thoracic radiologists established seven so-called S modifiers:
- Coronary artery calcification (moderate or higher degree [more than isolated calcification within a segment])
- Emphysema (moderate or higher degree [> 5% of any lung zone])
- Interstitial lung abnormalities (> 5% of any lung zone)
- Extrapulmonary malignancy
- Aortic aneurysm (≥ 4.5 cm)
- Pleural or pericardial effusion (large amount)
- Pneumonia or active pulmonary tuberculosis
Researchers tracked the S modifiers among 125,600 participants (mostly men around age 62) who underwent baseline LCS between August 2019 and December 2020. Their analysis found that coronary artery calcification was most prevalent at 15.1%, followed by emphysema at 13.8%, interstitial lung abnormalities (ILAs) at 2.7%, and pulmonary infection at 0.9%.
However, all S modifiers were associated with increased all-cause mortality, Kim and colleagues noted. Importantly, using latent class analysis (LCA), the group identified a stepwise increase in mortality across four distinct classes of S-modifier clusters (co-occurrences) among LCS participants.
Class 1 (135 participants) comprised rare but high-risk S modifiers associated with serious health conditions, including extrapulmonary malignancy, aortic aneurysm, or pleural or pericardial effusion. Pleural or pericardial effusion showed the strongest association with all-cause mortality. Both extrapulmonary malignancy and aortic aneurysm were associated with more than threefold increased risk, according to the group.
Class 2 (2,994 participants) was defined by ILA, often coexisting with coronary artery calcification and/or emphysema, indicative of multiple chronic conditions. ILA demonstrated a more than twofold increased risk.
Class 3 (18,071 participants) was primarily characterized by coronary artery calcification, with some participants also exhibiting emphysema. Coronary artery calcification was associated with a 41% increased risk of all-cause mortality, while emphysema showed a 15% higher mortality risk.
Class 4 (12,841 participants) included individuals with isolated emphysema. Class 4 indicated a 22% higher risk.
In addition, a secondary analysis revealed that pulmonary infection was associated with a 75% higher risk of all-cause mortality.
"In clinical practice, when an S modifier is detected, radiologists and clinicians should actively assess for other coexisting modifiers and consider referral, closer follow-up, or additional diagnostic evaluation," Kim and colleagues advised. "Although further validation is warranted, these findings highlight the potential of pattern-based risk stratification to inform participant management and optimize screening resources."
This study also highlighted the need for standardized definitions of incidental findings to ensure comparability across studies and populations.
Find the complete study, including Korea's mandated imaging parameters for LCS, here.
