LEP and lung cancer: Additionally, the subgroup analysis of treatment status indicated there is no statistical significance between serum leptin concentrations and lung cancer in the non-treatment group (SMD=-0.65, 95%CI=-1.57–0.26, P=0.159), but there was a statistical association in the group that did not reported whether the patients received any treatment (SMD=0.87, 95%CI=0.30–1.44, P=0.003).