Compared with CX3CL1 in the serum samples from the normal control groups (0.51 ± 0.03 ng/ml), serum samples from patients with lung cancer (P < 0.01), kidney cancer (P < 0.05) and prostate cancer (P < 0.05) contained significantly higher levels of CX3CL1, whereas those from patients with spinal metastases from liver cancer and breast cancer had a tendency to contain higher levels of CX3CL1 but without significance. This evidence concerns the gene CX3CL1 and lung cancer.