Risk of lung cancer in relation to contiguous windows of endotoxin exposure among female textile workers in Shanghai.

Publication Type:

Journal Article

Source:

Cancer causes & control : CCC, Volume 22, Issue 10, p.1397-1404 (2011)

Keywords:

2011, Case-Control Studies, Center-Authored Paper, China, Cohort Studies, Endotoxins, Female, Follow-Up Studies, Humans, Lung Neoplasms, Middle Aged, Nonlinear Dynamics, Occupational Diseases, Occupational Exposure, Public Health Sciences Division, Risk Factors, September 2011, Textile Industry, Textiles

Abstract:

OBJECTIVE: Exposure to endotoxin has been consistently associated with a reduced risk of lung cancer. However, there is a paucity of information regarding temporal aspects of this relationship. The objective of this study was to investigate the associations between contiguous windows of endotoxin exposure and risk of lung cancer. METHODS: Data were reanalyzed from a case-cohort study (602 cases, 3,038 subcohort) of female textile workers in Shanghai, China. Cumulative endotoxin exposure was partitioned into two windows: ≥20 and <20 years before risk. Exposure-response relations were examined using categorical and non-linear (semi-parametric) models, accounting for confounding by previous exposure windows. RESULTS: There was an inverse trend of decreasing risk of lung cancer associated with increasing levels of endotoxin exposure ≥20 years before risk (p trend = 0.02). Women in the highest two categories of cumulative exposures had hazard ratios of 0.78 (95% CI 0.60-1.03) and 0.77 (95% CI 0.58-1.02) for lung cancer, respectively, in comparison with unexposed textile workers. There was, however, a weaker association and not statistically significant between lung cancer and endotoxin exposure accumulated in the more recent window (<20 years before risk). CONCLUSION: Results provide further evidence that endotoxin exposure that occurred 20 years or more before risk confers the strongest protection against lung cancer, indicating a possible early anti-carcinogenic effect. Further studies are needed to better understand the underlying biological mechanisms for this effect.