CXCL12 and neoplasm: In particular, we explored the association of the baseline circulating levels of VEGF, PDGF-AA, PDGF-AB/BB, stromal cell-derived factor-1 (SDF-1), osteopontin (OPN) and carcinoembryonic antigen (CEA) with tumor burden as shown by radiologic assessment, and with clinical benefit from BEV as measured by progression-free survival (PFS) and overall survival (OS).