Objective: A Mendelian randomization (MR) analysis was performed to assess the relationship between tea consumption and cancer. Methods: There were 100 639 participants with the information of gene sequencing of whole genome in the China Kadoorie Biobank. After excluding those with cancer at baseline survey, a total of 100 218 participants were included in this study. The baseline information about tea consumption were analyzed, including daily tea consumption or not, cups of daily tea consumption, and grams of daily tea consumption. We used the two-stage least square method to evaluate the associations between three tea consumption variables and incidence of cancer and some subtypes, including stomach cancer, liver and intrahepatic bile ducts cancer, colorectal cancer, tracheobronchial and lung cancer, and female breast cancer. Multivariable MR and analysis only among nondrinkers were used to control the impact of alcohol consumption. Sensitivity analyses were also performed, including inverse variance weighting, weighted median, and MR-Egger. Results: We used 54, 42, and 28 SNPs to construct non-weighted genetic risk scores as instrumental variables for daily tea consumption or not, cups of daily tea consumption, and grams of daily tea consumption, respectively. During an average of (11.4±3.0) years of follow-up, 6 886 cases of cancer were recorded. After adjusting for age, age2, sex, region, array type, and the first 12 genetic principal components, there were no significant associations of three tea consumption variables with the incidence of cancer and cancer subtypes. Compared with non-daily tea drinkers, the HR (95%CI) of daily tea drinkers for cancer and some subtypes, including stomach cancer, liver and intrahepatic bile ducts cancer, colorectal cancer, tracheobronchial and lung cancer, and female breast cancer, are respectively 0.99 (0.78-1.26), 1.17 (0.58-2.36), 0.86 (0.40-1.84), 0.85 (0.42-1.73), 1.39 (0.85-2.26) and 0.63 (0.28-1.38). After controlling the impact of alcohol consumption and performing multiple sensitivity analyses, the results were similar. Conclusion: There is no causal relationship between tea consumption and risk of cancer in population in China.
目的： 采用孟德尔随机化（MR）方法探讨饮茶与恶性肿瘤发病之间的关联。 方法： 利用中国慢性病前瞻性研究中100 639名具有全基因组基因分型数据的研究对象，剔除基线时患有恶性肿瘤的个体，最终纳入分析100 218名。饮茶信息为基线自报，按是否每日饮茶、每日饮茶杯数、每日饮茶克数分别进行分析。采用二阶段最小二乘回归模型计算3个饮茶变量与随访期间新发的全部恶性肿瘤及多种类型恶性肿瘤（胃癌、肝和肝内胆管癌、结肠直肠癌、气管/支气管和肺癌以及女性乳腺癌）的关联。为控制饮酒行为的影响，进一步采用多变量MR法或限制在不饮酒人群中进行分析。利用逆方差加权、加权中位数法、MR-Egger法等进行敏感性分析。 结果： 分别使用54、42、28个SNP位点构建非加权遗传风险评分作为上述3个饮茶变量的工具变量。研究对象随访（11.4±3.0）年，期间确定新发的恶性肿瘤6 886名。模型中调整年龄、年龄2、性别、地区、芯片类型及12个遗传主成分后，MR分析的结果显示，饮茶与全部恶性肿瘤以及各种类型的恶性肿瘤的发病无统计学关联。相比于非每日饮茶者，每日饮茶者的全部恶性肿瘤及部分亚型（胃癌、肝和肝内胆管癌、结肠直肠癌、气管/支气管和肺癌以及女性乳腺癌）的发病风险比（HR）值（95%CI）分别为0.99（0.78~1.26）、1.17（0.58~2.36）、0.86（0.40~1.84）、0.85（0.42~1.73）、1.39（0.85~2.26）以及0.63（0.28~1.38）。控制饮酒的影响以及多种敏感性分析显示类似的结果。 结论： 在中国人群中，本研究证据不支持饮茶与恶性肿瘤发病之间的因果关联。.