In a meta-analysis of 38 studies involving 5807 patients, high CXCL12 expression was associated with reduced overall survival in patients with esophagogastric (Hazard Ratio (HR) 2.08; 95% Confidence Interval (CI): 1.31–3.33, p = 0.002), pancreatic (HR 1.54; 95% CI: 1.21–1.97, p = 0.0005), and lung cancer (HR 1.37; 95% CI: 1.08–1.75, p = 0.01), whereas in breast cancer patients, high CXCL12 expression conferred an overall survival advantage (HR 0.5; 95% CI: 0.38–0.66, p < 0.00001) [16]. This evidence concerns the gene CXCL12 and lung cancer.