For CRC patients with lung metastasis, studies have revealed that C-X-C chemokine receptor type 7 (CXCR7) and C-X-C motif chemokine ligand 12 (CXCL12) expression is significantly higher in metastatic site than in primary lesion, and CXCL12 expression is higher in nontumor lung tissue of patients with CRC than in control lung tissue with benign lesion. This evidence concerns the gene CXCL12 and colorectal carcinoma.