A meta-analysis of association between serum iron levels and lung cancer risk

Many studies conducted on the relationship between serum iron levels and lung cancer risk had produced inconsistent results. We therefore conducted a meta-analysis to determine whether serum iron levels were lower in lung cancer patients compared to those in controls. A literature survey was conducted by searching the PubMed, WanFang, CNKI, and SinoMed databases for articles published as of Mar 1, 2018. Standard mean differences (SMD) with the corresponding 95% confidence intervals (CI) were executed by Stata 12.0 software. A total of 13 publications involving 1118 lung cancer patients and 832 controls were included in our study. The combined results showed that serum iron levels in lung cancer cases had no significantly lower when compared to those in controls [summary SMD = -0.125, 95% CI= -0.439, 0.189, Z = 0.78, p for Z test= 0.435], with high heterogeneity (I-2= 89.9%, P< 0.001) found. In the stratified analysis by geographic locations, consistent results were found for serum iron levels between lung cancer patients and controls both in Asian populations [summary SMD = -0.113, 95% CI= -0.471, 0.245] and European populations [summary SMD = -0.215, 95% CI= -0.835, 0.404]. Publication bias was not found when evaluated by Begg's funnel plot and Egger's regression asymmetry test. In summary, the current study showed that serum iron levels had no significant association on lung cancer risk.