Association between serum copper levels and cervical cancer risk: a meta-analysis

Whether serum copper levels were higher in patients with cervical cancer than that in controls was controversial. Hence, we conducted the present study to explore the relationship between serum copper levels and cervical cancer. We searched PubMed, WanFang, and China National Knowledge Internet (CNKI) for relevant studies before November 30, 2017. Standardized mean difference (SMD) and 95% confidence interval (Cl) were used to combine results across studies using the random-effect model. A total of 14 publications involving 747 patients with cervical cancer and 1014 controls were eligible through inclusion criteria. In comparison with controls, serum copper levels were significantly higher in patients with cervical cancer [summary SMD = 1.35; 95%CI: 0.10-2.59], with significant heterogeneity (I-2 = 98.8%; P < 0.001) was found. Significant association was also found among Asian populations [summary SMD = 1.39; 95%CI: 0.06-2.71]. The association was positive in subgroup analysis of population-based case-control studies (PBCC) [summary SMD = 1.64; 95%CI: 0.02-3.34], but not in hospital-based case-control studies (HBCC). Through a sensitivity analysis, we did not identify any single study to strongly influence the results of our serum copper levels and cervical cancer risk. No publication bias was found in our analysis. In conclusion, our study provided significant evidence of higher serum copper levels in patients with cervical cancer than in controls, suggesting that serum copper exposure was a risk factor on cervical cancer.