Association between Chlamydia pneumoniae infection and lung cancer: a meta-analysis

BACKGROUND: The aim of this study is to explore the correlation between Chlamydia pneumoniae (C. pneumoniae) infection and lung carcinoma. METHODS: Databases of PubMed, Embase, Embase, Ovid, Wanfang and China National Knowledge Infrastructure (CNKI) database were investigated for eligible literatures from their establishments to February, 2019. Included studies were selected according to specific eligibility criteria. Statistical analysis was performed by RevMan 5.3 software. RESULTS: Thirteen studies with 2,553 lung carcinoma cases and 2,460 controls were eligible for meta-analysis. The pooled results indicated that the C. pneumoniae infection IgA significantly increased the risk of lung carcinoma (OR =3.19; 95% CI, 1.96–5.19; P<0.00001) by random effect model. And for serum IgG, the pooled OR was 2.02 (95% CI, 1.29–3.16; P<0.00001) by using the random effects model. The results indicated that the IgA positive rate was significantly higher in lung cancer patients than healthy controls. CONCLUSIONS: This meta-analysis revealed that C. pneumoniae infection may be a potential risk factor for lung carcinoma. However, due to its significant heterogeneity in the included studies, the consequence should be understood with caution.