[Mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence].

Objective: To evaluate the possible mediation effect of smoking and healthy diet score on the association between educational level and the risk of lung cancer incidence. Methods: After excluding individuals with missing educational levels and cancer information at baseline, 446 772 participants in the UK Biobank (UKB) prospective cohort study were included. Cox regression models were used to investigate the associations of educational level and smoking and healthy diet score with the incidence of lung cancer. Mediating effect analysis was conducted to analyze the mediating effect of smoking and healthy diet score on the correlation between educational level and lung cancer. Results: During a median follow-up of 7.13 years, 1 994 new- onset lung cancer cases were observed. Per 1 standard deviation (5 years) increase in educational level was associated with a 12% lower risk of lung cancer (HR=0.88, 95%CI: 0.84-0.92). The corresponding level 1-5 in the International Standard Classification for Education (ISCED) were mapped to UKB self-report highest qualification to estimate the educational level. A higher rank means a higher educational level. Compared with level ISCED-1, the HR(95%CI) of level ISCED-2, ISCED-3, ISCED-4 and ISCED-5 were respectively 0.83 (0.72-0.94), 0.67 (0.53-0.85), 0.76 (0.65-0.89) and 0.72 (0.64-0.80) for lung cancer. Education years were negatively correlated with smoking, with β coefficients (95%CI) being -0.079 (-0.081- -0.077), but positively correlated with healthy diet score (β=0.042, 95%CI: 0.039-0.045). Analysis of mediating effect indicated that the association of educational level with lung cancer risk was mediated by smoking and healthy diet score, the proportions of mediating effect were 38.952% (95%CI: 31.802%-51.659%) and 1.784% (95%CI: 0.405%-3.713%), respectively. Conclusion: Smoking and healthy diet score might mediate the effect of educational level on the incidence of lung cancer, indicating that improving the level of education can reduce the risk of lung cancer by changing lifestyles such as smoking and diet.目的： 探讨吸烟和健康饮食评分在文化程度与肺癌发病风险关联中的中介效应。 方法： 基于英国生物银行（UKB）前瞻性队列研究数据，剔除文化程度信息缺失及基线患有癌症的个体后，最终纳入446 772名研究对象。采用Cox比例风险回归模型估计文化程度与肺癌发病风险的关联以及吸烟和健康饮食评分与肺癌发病的关联，采用中介效应模型分析吸烟和健康饮食评分在文化程度和肺癌风险关联中的中介效应。 结果： 在7.13年的中位随访时间内，新发肺癌1 994例。受教育年数每增加一个标准差（5年），肺癌风险降低12%（HR=0.88，95%CI：0.84~0.92）。根据UKB自我报告的最高学历转换为国际教育代码分类标准（ISCED）中对应的1~5级，级数越大代表文化程度越高。与ISCED-1者相比，ISCED-2、ISCED-3、ISCED-4和ISCED-5人群的肺癌发病HR值（95%CI）依次为0.83（0.72~0.94）、0.67（0.53~0.85）、0.76（0.65~0.89）和0.72（0.64~0.80）。文化程度与吸烟呈负相关（β=-0.079，95%CI：-0.081~-0.077），与健康饮食评分呈正相关（β=0.042，95%CI：0.039~0.045）。中介效应分析显示，吸烟与健康饮食评分在文化程度与肺癌的关联中存在中介效应，中介比例分别为38.952%（95%CI：31.802%~51.659%）和1.784%（95%CI：0.405%~3.713%）。 结论： 吸烟和健康饮食评分可能介导文化程度对肺癌发病的影响，这表明提高文化程度可能通过改变吸烟和饮食等生活方式降低肺癌发病风险。.