In our study, we found that pericardial effusion is associated with top-QTc prolongation, with possible mechanisms as follows: (1) In advanced NSCLC patients, pericardial effusion may contain tumor-secreted inflammatory cytokines that could induce inflammation and fibrosis, leading to prolongation of QT interval, such as interleukin (IL)-1, IL-6, IL-8, IL-10, TNF-α, and TGF-β (26, 27). This evidence concerns the gene IL6 and pericardial effusion.