Coronary atherosclerosis as an incidental finding within the lung cancer screening program

Purpose: Smoking is a leading cause of preventable morbidity and mortality worldwide, contributing to lung cancer, COPD, stroke, and coronary heart disease. Lung cancer remains the deadliest malignancy, with smoking as its main etiologic factor. Early detection via low-dose computed tomography (LDCT) reduces mortality. Since 2019, a national feasibility study on LDCT-based lung cancer screening (LCS) has been conducted at University Hospital Zurich. Because smoking also increases coronary atherosclerosis risk, this study aimed to determine the prevalence, severity, and clinical significance of coronary artery calcification (CAC) as an incidental finding in LCS participants and assess its relationship with age and smoking exposure. Methods: 201 participants from the Swiss LCS cohort were retrospectively analyzed. All were current or former heavy smokers meeting national screening criteria. LDCT scans were assessed by two thoracic radiologists using the SHEMESH score, grading calcification in LM, LAD, LCx, and RCA from 0 (absent) to 3 (severe), with total CAC scores 0-12. Relationships between CAC, age, and smoking exposure (pack-years) were analyzed using a generalized linear mixed model. Participants with CAC > 4 were advised to undergo stress testing and followed for four years for cardiologic evaluation or cardiovascular events. Results: CAC was detected in 55.7% (112/201): 30.8% mild (1-3), 15.9% moderate (4-6), and 8.9% severe (7-12). CAC correlated significantly with age (p = 0.032) and pack-years (p = 0.011). Among 50 participants with CAC > 4, one was lost to follow-up; two did not undergo evaluation due to palliative care or non-cardiac death; 18 are under assessment. Eight (19.5%) had prior cardiac events; 18 had negative stress tests. Three (6.3%) had positive tests or symptoms, leading to angiography and stent placement; in two cases, the treated vessel matched the highest CAC score. Most calcifications were in LAD and RCA. Nine of 49 reported exertional dyspnea or atypical chest discomfort, prompting further evaluation. Conclusions: Incidental CAC was highly prevalent in smokers undergoing LDCT screening, with severity linked to age and cumulative tobacco exposure. CAC detection during LCS offers an opportunity for cardiovascular risk assessment without added radiation or scan time. Integrating CAC evaluation into LDCT protocols could enhance early identification of at-risk individuals, support preventive cardiology, and improve outcomes. This study supports LDCT screening as a dual-purpose tool against lung cancer and coronary atherosclerosis, aligning with precision preventive medicine strategies.