Effect Of Endotoxin Exposure On Lung Cancer Risk In Cotton Textile Mills:A Meta-Analysis

Background To evaluate the relationship between occupational exposure to endotoxin and the risk of lung cancer among workers in cotton textile mills.Methods Relevant studies were searched in Pubmed, Embase, MEDLINE, Cochrane Library, CNKI, Wan Fang, VIP and CBM databases before December 31,2015. Two investigators selected eligible studies according to inclusion criteria and extracted the data independently. The methodological quality of included studies were assessed through the New-Castle Ottawa Scale (NOS) for observational studies. Meta-analyses were performed by using Stata 12.0 software.Results Fourteen cotton textile studies were finally included in this meta-analysis. Substantial heterogeneity was found among studies (I2 76.5%, p= 0.000).The pooled relative risk (RR) between endotoxin exposure and lung cancer was 0.94 (0.79-1.11) for textile workers. After removing one study that inducing the heterogeneity according to a ten-year period of follow-up, the heterogeneity disappeared and the summary risk of lung cancer turned out to be a significant result with RR 0.87 (95% CI,0.81-0.93). Significant protective effects were showed in several subgroups as follows:case-control study,0.70 (95% CI,0.58-0.84); both gender, male 0.83 (95%CI,0.75-0.93), female 0.89, (95%CI,0.82-0.98); smoke adjustment,0.83 (95% CI,0.76-0.91) and smoke unadjustment 0.91 (95% CI,0.82-1.00); USA,0.62 (95% CI,0.47-0.83) and China,0.84 (95% CI,0.77-0.92); morbidity as outcome,0.86 (95% CI,0.78-0.93) and mortality as outcome,0.89 (95% CI,0.80-1.00); follow up 10-20 years,0.89 (95% CI,0.80-0.99) and follow up 21-30 years 0.87 (95% CI,0.77-0.99). The meta-RR was stable regardless of ruling out any one of the 13 studies in sensitive analysis. There was no evidence of publication bias among studies according to both Egger’s test and Begg’s test.Conclusions This meta-analysis supported that endotoxin exposure is associated with decreased lung cancer risk in cotton textile mills. Whether the anti-cancer effect of endotoxin exposure influenced by inadequate smoke adjustment is still unclear right now.