Association between serum copper/zinc ratio and lung cancer: A systematic review with meta-analysis

Numerous studies have investigated the relationship between serum copper/zinc ratio and lung cancer. However, the results are inconsistent. Therefore, we evaluated the association between copper/zinc ratio and lung cancer.

Observational studies reporting serum copper/zinc ratio in lung cancer patients and controls were identified from PubMed, Web of Science, EMBASE, CNKI and Wanfang databases online before December 2021. Summary standard mean difference (SMD) and the corresponding 95 % confidence interval (95 % CI) were applied to compare the serum serum copper/zinc ratio between lung cancer patients and controls using a random-effects model.

Thirty-nine articles including 3598 lung cancer patients, 1402 benign lung diseases, and 3314 healthy controls were included in this study. The pooled results showed that the lung cancer patients had significantly higher serum copper/zinc ratio than healthy controls [SMD (95 % CI): 1.62 (1.31, 1.93)] and patients with benign lung diseases [SMD (95 % CI): 0.60 (0.36, 0.84)]. The results were robust according to sensitivity analysis. Meanwhile, consistent results were obtained both in European populations and Asian populations. Moreover, serum copper/zinc ratio was significant higher in patients with advanced stage of lung cancer than that in patients with early stage of lung cancer.

The results showed that elevated serum copper/zinc ratio might be associated with increased risk of lung cancer.