Coronary atherosclerosis has a protective genetic causal effect against lung squamous cell carcinoma: A bidirectional...

Many observational studies have demonstrated an association between coronary atherosclerosis (CAS) and lung cancer (LUCA). However, there is not enough evidence to justify a direct genetic causal effect between CAS and LUCA as well as its subtypes. This study aimed to use Mendelian randomization (MR) analysis to assess the causal relationship between CAS and LUCA as well as its subtypes at the genetic level. This study was designed following the STROBE-MR guidelines and was a bidirectional two-sample MR analysis based on the context of the European population. It extracted genome-wide association study (GWAS) data of 51,589 CAS patients from the FinnGen Biobank database and extracted GWAS data of patients with LUCA and its subtypes from the IEU open GWAS database for MR analysis. In addition, this study used heterogeneity tests, sensitivity analyses, and multiple validity analyses to ensure the accuracy and robustness of the results. In the forward MR results, there was a statistically significant difference between CAS and LUCA (odds ratio [OR]: 0.88, 95% confidence interval [95% CI]: 0.82-0.95, P = .00099), and in the subtype analysis, there was a statistically significant difference between CAS and lung squamous cell carcinoma (LUSC) (OR [95% CI]: 0.84 [0.75-0.94], P = .00322); there was no statistical significance between CAS and either lung adenocarcinoma or small cell LUCA (OR [95% CI]: 0.93 [0.84-1.03], P = .1426; OR [95% CI]: 0.87 [0.73-1.03], P = .1145). In the reverse MR results, there was no statistical significance between LUCA and CAS as well as between LUSC and CAS (OR [95% CI]: 0.96 [0.92-1.01], P = .099; OR [95% CI]: 1.03 [0.95-1.10], P = .382). The study results showed that CAS has a genetic causal effect on LUCA and its subtype LUSC and that the effect is protective. Further studies are required to explore the underlying mechanisms.