Association between the Severity of Coronary Artery Disease and Lung Cancer: A Pilot Cross-Sectional Study

Background: The direct relationship between coronary artery disease (CAD) and lung cancer is not well known. Objective: To investigate the association between the anatomical severity of CAD and lung cancer. Methods: Three-hundred study patients, including 75 recently diagnosed lung cancer patients and 225 matched non-cancer patients, underwent coronary angiography during hospitalization without previous percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). The SYNTAX score (SXscore) was used to assess the severity of CAD. A high SXscore (SXhigh) grade was defined as SXscore > 15 (the highest quartile of the SXscore). The Cochran-Armitage test for trend was used to assess the distribution of patients' SXscores. Logistic regression analysis was used to assess the association between the severity of CAD and lung cancer. P-values were set when significance level was 5%. Results: The distribution trend of patients' SXscore by quartiles was different between lung cancer patients and control patients ( from the lowest to the highest quartile: 20.0%, 20.0%, 24.0%, 36.0% vs. 26.7%, 26.2%, 25.8%, 21.3%, p=0.022). The SX high rate was higher in lung cancer patients than in control patients (36.0% vs. 21.3%, p=0.011).The highest quartile of the SXscore showed higher risk of lung cancer in comparison to the lowest quartile (OR: 2,250, 95%CI: 1,077 to 4,699; P-trend= 0.016). After adjustment, patients in the highest quartile of the SXscore had higher risk of lung cancer (OR: 2,149, 95%CI: 1,008 to 4,584; P-trend= 0.028). Patients with high SXscore (> 15) had 1,985 times more chances of having lung cancer (95% CI: 1,105-3,563, P= 0.022). Conclusions: The anatomical severity of CAD is associated with the risk of lung cancer, which indicates that a thorough lung cancer screening may be significant among severe CAD patients.