CXCL12 and cancer: By contrast, decreased expression of the PR in cancer-associated stroma may contribute to elevated SDF-1 and interleukin-6 levels in prostate tumors and enhance prostate tumor progression, whereas the high tumor stromal cell density level (p = 0.045) of PR was significantly associated with tumor progression and clinical failure in tumor tissue of patients with T1-3N0 PCa undergoing RP [27, 45].