BACKGROUND The study aims are to evaluate the associations between nasopharyngeal carcinoma (NPC) risk and cigarette smoking and to explore the effects of cigarette smoking on Epstein-Barr virus (EBV) infection for NPC risk. METHODS 1235 male NPC cases and 1262 hospital-based male controls matched to cases were recruited across six collaborative hospitals between 2010 and 2014. Using a standardized questionnaire, information on cigarette smoking and other potential risk factors for NPC was obtained. Blood was collected and used for anti-EBV VCA IgA and anti-EBV EA-EBNA1 IgA testing using standard methods. Unconditional logistic regression analysis was used to estimate odds ratio (OR) with 95% confidence interval (CI) for each risk factor after adjusting for confounders. RESULTS 63.6% of cases and 44.0% of controls reported ever smoking cigarettes. After full adjustment, current smokers had a significant 1.60-fold (95% CI = 1.30-1.97) and former smokers a borderline significant 1.27-fold (95% CI = 1.00-1.60) increased NPC risk compared to never smokers. NPC risk increased with increasing duration, intensity, and pack-years of cigarette smoking but not with age at smoking initiation. Among controls, anti-EBV VCA IgA seropositivity rate was higher in current smokers than never smokers (14.0% vs 8.4%; OR = 1.82; 95% CI = 1.19-2.79). Mediation analyses showed that more than 90% of the cigarette smoking effect on NPC risk is mediated through anti-EBV VCA IgA. CONCLUSION This study confirms the association between long-term cigarette smoking and NPC and demonstrates that current smoking is associated with seropositivity of anti-EBV VCA IgA antibodies.

中文翻译：

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抽烟会通过提高针对爱泼斯坦-巴尔病毒衣壳抗原的IgA抗体水平而增加鼻咽癌的风险：一项调解分析。

背景技术本研究旨在评估鼻咽癌（NPC）风险与吸烟之间的关系，并探讨吸烟对爱泼斯坦-巴尔病毒（EBV）感染对NPC风险的影响。方法在2010年至2014年之间，从六家合作医院中招募了1235例男性NPC病例和1262例与病例匹配的医院男性对照。收集血液，并使用标准方法将其用于抗EBV VCA IgA和抗EBV EA-EBNA1 IgA测试。在对混杂因素进行调整之后，使用无条件逻辑回归分析来估计每个风险因素的比值比（OR）和95％置信区间（CI）。结果63.6％的病例和44。0％的对照组报告曾经吸烟。经过全面调整后，与从未吸烟者相比，当前吸烟者的NPC风险增加了1.60倍（95％CI = 1.30-1.97），而以前的吸烟者的NPC风险增加了1.27倍（95％CI = 1.00-1.60）。NPC风险随着吸烟时间，强度和装箱年限的增加而增加，但不随开始吸烟的年龄而增加。在对照组中，当前吸烟者的抗EBV VCA IgA血清阳性率高于从未吸烟者（14.0％比8.4％； OR = 1.82； 95％CI = 1.19-2.79）。调解分析表明，吸烟对NPC风险的90％以上是通过抗EBV VCA IgA介导的。