The relation of passive smoking with cervical cancer: A systematic review and meta-analysis.

Background: Published studies about passive smoking and cervical cancer have found inconsistent results. Hence, the present meta-analysis was performed to assess this association. Methods: A systematical search was performed to identify eligible cohort and case-control studies in PubMed, Scopus, Elsevier ScienceDirect, and Web of Science databases (up to March, 2018). The quality of included studies was assessed by the NewcastleOttawa quality scale (NOS). The random effects model (REM) was used to calculate the pooled odds ratio (ORs). Subgroup and sensitivity analyses were performed. Publication bias was assessed by funnel plot, using Begg's test and Egger's test. Results: Around 14 eligible studies were included for analysis, which included a total of 384,995 participants. The pooled ORs of passive smoking with cervical cancer risk was 1.70 (95% CI: 1.40-2.07, I-2=64.3%). Subgroups stratified by continent, study design, quality score, and cervical cancer types/phases suggested that the result was robust. For instance, the pooled ORs for the cohort and case-control studies was 1.37 (95% CI: 1.16-1.62, I-2=0%) and 2.09 (95% CI: 1.52-2.89, I-2=76.6%), respectively. The pooled ORs ranged from 1.61 (95% CI: 1.34-1.92) to 1.77 (95% CI: 1.44-2.16) after one study was removed each time in the sensitivity analyses, indicating that the result was stable. Publication bias was detected by funnel plot and Egger's tests. The recalculated ORs were 1.33 (95% CI: 1.21-1.47). Conclusions: This meta-analysis provides evidence that passive smoking is associated with an increased risk of cervical cancer.