A study of 71 patients with HNSCC assessing the tissue expression levels of SDF-1 and CXCR4 found that patients with low SDF-1 had poorer metastasis-free survival (P = 0.026), disease-free survival (P = 0.006) and overall survival rates (P = 0.002) [69]. The gene discussed is CXCL12; the disease is head and neck squamous cell carcinoma.