Interestingly, we found that the association between tumor expression of CXCL12 and OS was stronger in studies with a high CXCL12 expression defined as above the median density value as compared to that as any positive expression of CXCL12 (HR: 2.63 vs. 1.61, p for subgroup difference = 0.03; Fig. 3A). This evidence concerns the gene CXCL12 and neoplasm.