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

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.

Potential Roles of Innate Immune Chemokine and Cytokine Network on Lipopolysaccharide-Based Therapeutic Approach in Ovarian Cancer

“…Several occupational groups, including agricultural and cotton textile workers exposed to organic dusts contaminated by endotoxins, showed a reduced lung cancer risk (Fig. 1) (1214202122232425262728293031323334353637383940). On one hand, some reports on lung cancer indicated no change (41), while other reports indicated increased cancer risk (4243).…”

Occupational exposure to textile dust and lung cancer risk: Results from the ICARE Study

“…Our results suggest that the risk of lung cancer was higher among workers who used a protective mask than among those who did not, which could corroborate this interpretation. An analysis of the case‐cohort of women textile workers in Shanghai suggested that heavy exposure to endotoxins was associated with decreased hazard ratios when incurred at least 20 years before lung cancer diagnosis, but not when more recent . The authors speculated on the existence of a threshold or a possible anti‐carcinogenic effect of endotoxins at early stages of lung cancer initiation, but more recent analyses of the same cohort did not replicate these results …”

“…When analyses were based on duration of exposure, we found an inverse dose response trend ( P = 0.03), although the decreased ORs observed for each quartile were not statistically significant. Unfortunately, the meta‐analysis by Lenters et al did not report overall risk estimates according to duration, but some studies have reported an inverse dose‐response relationship with duration …”

Textile industry and occupational cancer

“… 15 Gallagher et al, 2013 [ 52 ] Female textile workers Lung cancer Cancer risk was higher in women with a surgical menopause (HR = 1.64, 95 % CI 0.96–2.79) than in those with a natural menopause (HR = 1.35, 95 % CI 0.84–2.18) demonstrating biological role of hormones in lung carcinogenesis. 16 Agalliu et al, 2011 [ 39 ] Female textile workers Lung cancer Endotoxin exposure that occurred 20 years or more before risk confers the strongest protection against lung cancer, indicating a possible early anti-carcinogenic effect. 17 Checkoway et al, 2011 [ 38 ] Female textile workers Lung Cancer No associations were observed for lung cancer with wool, silk or synthetic fibre dusts.…”

“…But in this study, no associations were observed for lung cancer with wool, silk, synthetic fibre dust or with other agents. Agalliu et al [ 39 ] investigated the associations between contiguous windows of endotoxin exposure and risk of lung cancer, and reported that endotoxin is consistently associated with a reduced risk of lung cancer. Data from 602 cases of female textile workers was evaluated in Shanghai, China and an inverse risk trend of lung cancer with increasing levels of endotoxin exposure was found.…”