Occupational exposure to endotoxins and small cell lung cancer: a systematic review with meta-analysis

ABSTRACT

The relationship of occupational exposure to endotoxins with different histologic subtypes of lung cancer has not been established. Our objective was to conduct a systematic review with meta-analysis to assess the effect of exposure to endotoxins on the development of small cell lung cancer (SCLC). A bibliographic search was conducted using MEDLINE, Embase, CENTRAL, and Web of Science databases until December 2022, including all cohort and/or case–control studies that examined occupational exposure to endotoxins and SCLC. Risk of bias was assessed using the U.S. Office of Health Assessment and Translation tool. A random effects model was applied, publication bias were assessed, and a sensitivity analysis was conducted. Four papers were selected for meta-analysis purposes. A total of 144 incident cases of SCLC and 897 population or hospital controls were included. Occupational exposure to endotoxins was considered for textile/leather industry and agricultural sector workers exposed to endotoxins originating from wool, cotton, or leather dust. Except for one study, all investigations were classified as having a low probability of risk of biases. The results of the meta-analysis were not statistically significant (pooled OR: 0.86; 95% CI:0.69-1.08). In addition, neither between-study heterogeneity (I²=0%;p=0.92) nor publication bias was observed (p=0.49). The results of the sensitivity analysis, after including five studies that assessed the risk of SCLC among textile industry and crop/livestock farm workers (not specifically exposed to endotoxins), showed a negative statistically non-significant association and low between-study heterogeneity (pooled OR: 0.90; 95% CI:0.79-1.02; I²=22%;p=0.23). Subjects exposed to occupational exposure to endotoxins seem to exhibit a negative association with the development of SCLC, although the results are not conclusive.

KEYWORDS:

• Occupational exposure
• endotoxins
• small cell carcinoma
• case–control studies
• meta-analysis

Abbreviations

CI	=	Confidence interval
IARC	=	International Agency for Research on Cancer
LC	=	Lung cancer
OR	=	Odds ratio
OHAT	=	Office of Health Assessment and Translation
PRISMA	=	Preferred Reporting Items for Systematic Reviews and Meta-Analyses
RR	=	Relative risk
SCLC	=	Small cell lung cancer
USA	=	United States of America

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data generated or analyzed during this study can be found within the published article and its supplementary files.

Additional information

Funding

This work was supported by a research project (1215/2022) awarded by the Spanish Society of Respiratory Pathology (SEPAR), entitled “Occupation and lung cancer. A pooling study in Northwestern Spain”.