Department of Epidemiology and Population Health, Albert Einstein College of Medicine, 1300 Morris Park Ave., Belfer Bldg Room 1315-B, Bronx, NY, USA.
Cancer Causes Control. 2011 Oct;22(10):1397-404. doi: 10.1007/s10552-011-9812-x. Epub 2011 Jul 6.
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.
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.
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).
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.
接触内毒素与肺癌风险降低相关，这一观点已得到一致证实。然而，目前有关该相关性时间方面的信息还很有限。本研究旨在调查内毒素接触的连续时间窗与肺癌风险之间的关联。
本研究对来自中国上海女性纺织工人病例-对照研究（602 例病例，3038 名亚队列成员）的数据进行了重新分析。将累积内毒素暴露分为两个时间窗：风险前 20 年及以上和<20 年。使用分类和非线性（半参数）模型，在考虑先前暴露时间窗的混杂因素后，检查暴露-反应关系。
与风险前 20 年累积内毒素暴露水平较高相关的肺癌风险呈下降趋势（趋势 P 值=0.02）。与未暴露于纺织工作的女性相比，累积暴露量最高的两个类别的女性肺癌风险比（HR）分别为 0.78（95%置信区间[CI]：0.60-1.03）和 0.77（95%CI：0.58-1.02）。然而，与最近的时间窗（风险前<20 年）中累积的内毒素暴露之间的关联较弱，且无统计学意义。
结果提供了进一步的证据，表明风险前 20 年或更早发生的内毒素暴露对肺癌的保护作用最强，表明可能存在早期抗癌作用。需要进一步的研究来更好地理解这种效应的潜在生物学机制。
