There were no significant differences of NE and MPO levels in serum and BAL fluid between the non-small cell lung cancer and small cell lung cancer (NE serum 512.19 ± 8.99 ng/mL vs. 537.72 ± 11.97 ng/mL, NE BAL fluid 316.53 ± 8.43 ng/mL vs. 332.65 ± 25.03 ng/mL, MPO serum 298.35 ± 13.16 ng/mL vs. 305.31 ± 17.32 ng/mL, MPO BAL fluid 114.09 ± 14.08 ng/mL vs. 130.83 ± 10.91 ng/mL, P > 0.05) as well as among various histological types of cancer (data not shown). The gene discussed is MPO; the disease is cancer.