High CXCL12 expression was associated with reduced overall survival in patients with esophagogastric (P = 0.002), pancreatic (P = 0.0005), and lung cancer (P = 0.01), whereas in breast cancer patients, high CXCL12 expression conferred an overall survival advantage (P < 0.001) [18]. This evidence concerns the gene CXCL12 and breast cancer.