Littman Alyson J, White Emily, Jackson Lisa A, Thornquist Mark D, Gaydos Charlotte A, Goodman Gary E, Vaughan Thomas L
Department of Epidemiology, University of Washington, 1100 Fairview Avenue North, PO Box 19024, Seattle 98109-1024, USA.
Cancer Epidemiol Biomarkers Prev. 2004 Oct;13(10):1624-30.
Infection with Chlamydia pneumoniae may be associated with an increased risk of lung cancer. We conducted a matched case-control study (508 pairs) nested within a large prospective study to investigate whether IgA antibody titers to C. pneumoniae measured by the microimmunofluorescence test are associated with lung cancer risk after controlling for confounders. Individuals with antibody titers > or = 16 had 1.2 times the risk of lung cancer (95% confidence interval, 0.9-1.6) compared to those with lower titers. There was a significant trend (P = 0.007) of increasing odds ratios with increasing IgA titers primarily due to an odds ratio of 2.8 (95% confidence interval, 1.1-6.7) associated with titers > or = 256. Lung cancer risk associated with IgA titers > or = 16 was stronger among former smokers. To better understand predictors of IgA seropositivity, we also examined demographic, lifestyle, dietary, and medical correlates of IgA titers > or = 16 among controls. Those with race not classified as White or Black were more likely to have IgA titers > or = 16; there were no significant differences in seropositivity by smoking behaviors. In summary, the adjusted odds ratio for lung cancer associated with IgA titers > or = 16 was compatible with a weakly positive association, although nondifferential measurement error of antibody titers may have resulted in a conservative bias. Future studies using precise measures of chronic C. pneumoniae status are needed to better determine the role of this organism in the etiology of lung cancer.
肺炎衣原体感染可能与肺癌风险增加有关。我们在一项大型前瞻性研究中进行了一项匹配病例对照研究（508对），以调查通过微量免疫荧光试验检测的肺炎衣原体IgA抗体滴度在控制混杂因素后是否与肺癌风险相关。抗体滴度≥16的个体患肺癌的风险是滴度较低者的1.2倍（95%置信区间，0.9 - 1.6）。随着IgA滴度升高，优势比有显著上升趋势（P = 0.007），这主要是由于滴度≥256时优势比为2.8（95%置信区间，1.1 - 6.7）。在既往吸烟者中，与IgA滴度≥16相关的肺癌风险更强。为了更好地了解IgA血清阳性的预测因素，我们还研究了对照组中IgA滴度≥16的人口统计学、生活方式、饮食和医学相关因素。种族未归类为白人或黑人的个体更有可能IgA滴度≥16；血清阳性在吸烟行为方面无显著差异。总之，与IgA滴度≥16相关的肺癌调整后优势比与弱阳性关联相符，尽管抗体滴度的非差异测量误差可能导致了保守性偏倚。需要未来研究采用慢性肺炎衣原体状态的精确测量方法，以更好地确定该病原体在肺癌病因学中的作用。
