Dairy consumption and risks of total and site-specific cancers in Chinese adults: an 11-year prospective study of 0.5 million people
Authors: Kakkoura Maria G. , Du Huaidong , Guo Yu , Yu Canqing , Yang Ling , Pei Pei , Chen Yiping , Sansome Sam , Chan Wing Ching , Yang Xiaoming , Fan Lei , Lv Jun , Chen Junshi , Li Liming , Key Timothy J. , Chen Zhengming ,   on behalf of the China Kadoorie Biobank (CKB) Collaborative Group, Chen Junshi , Chen Zhengming , Clarke Robert , Collins Rory , Guo Yu , Li Liming , Wang Chen , Lv Jun , Peto Richard , Walters Robin , Avery Daniel , Bennett Derrick , Boxall Ruth , Chan Ka Hung , Chang Yumei , Chen Yiping , Clarke Johnathan , Du Huaidong , Fairhurst-Hunter Zammy , Fry Hannah , Gilbert Simon , Hacker Alex , Hill Mike , Holmes Michael , Im Pek Kei , Iona Andri , Kakkoura Maria , Kartsonaki Christiana , Kerosi Rene , Lin Kuang , Mazidi Mohsen , Millwood Iona , Nie Qunhua , Pozarickij Alfred , Ryder Paul , Said Saredo , Sansome Sam , Schmidt Dan , Sherliker Paul , Sohoni Rajani , Stevens Becky , Turnbull Iain , Wang Lin , Wright Neil , Yang Ling , Yang Xiaoming , Yao Pang , Han Xiao , Hou Can , Xia Qingmei , Liu Chao , Pei Pei , Yu Canqing , Chen Naying , Liu Duo , Tang Zhenzhu , Chen Ningyu , Jiang Qilian , Lan Jian , Li Mingqiang , Liu Yun , Meng Fanwen , Meng Jinhuai , Pan Rong , Qin Yulu , Wang Ping , Wang Sisi , Wei Liuping , Zhou Liyuan , Dong Caixia , Ge Pengfei , Ren Xiaolan , Li Zhongxiao , Mao Enke , Wang Tao , Zhang Hui , Zhang Xi , Chen Jinyan , Hu Ximin , Wang Xiaohuan , Guo Zhendong , Li Huimei , Li Yilei , Weng Min , Wu Shukuan , Yan Shichun , Zou Mingyuan , Zhou Xue , Guo Ziyan , Kang Quan , Li Yanjie , Yu Bo , Xu Qinai , Chang Liang , Fan Lei , Feng Shixian , Zhang Ding , Zhou Gang , Gao Yulian , He Tianyou , He Pan , Hu Chen , Sun Huarong , Zhang Xukui , Chen Biyun , Fu Zhongxi , Huang Yuelong , Liu Huilin , Xu Qiaohua , Yin Li , Long Huajun , Xu Xin , Zhang Hao , Zhang Libo , Su Jian , Tao Ran , Wu Ming , Yang Jie , Zhou Jinyi , Zhou Yonglin , Hu Yihe , Hua Yujie , Liu Jianrong Jin Fang , Liu Jingchao , Lu Yan , Ma Liangcai , Tang Aiyu , Zhang Jun , Cheng Liang , Du Ranran , Gao Ruqin , Li Feifei , Li Shanpeng , Liu Yongmei , Ning Feng , Pang Zengchang , Sun Xiaohui , Tian Xiaocao , Wang Shaojie , Zhai Yaoming , Zhang Hua , Hou Wei , Lv Silu , Wang Junzheng , Chen Xiaofang , Wu Xianping , Zhang Ningmei , Zhou Weiwei , Li Jianguo , Liu Jiaqiu , Luo Guojin , Sun Qiang , Zhong Xunfu , Gong Weiwei , Hu Ruying , Wang Hao , Wan Meng , Yu Min , Chen Lingli , Gu Qijun , Pan Dongxia , Wang Chunmei , Xie Kaixu , Zhang Xiaoyi 
Published: May 2022

Abstract
Background
Previous studies of primarily Western populations have reported contrasting associations of dairy consumption with certain cancers, including a positive association with prostate cancer and inverse associations with colorectal and premenopausal breast cancers. However, there are limited data from China where cancer rates and levels of dairy consumption differ importantly from those in Western populations.

Methods
The prospective China Kadoorie Biobank study recruited ~0.5 million adults from ten diverse (five urban, five rural) areas across China during 2004–2008. Consumption frequency of major food groups, including dairy products, was collected at baseline and subsequent resurveys, using a validated interviewer-administered laptop-based food frequency questionnaire. To quantify the linear association of dairy intake and cancer risk and to account for regression dilution bias, the mean usual consumption amount for each baseline group was estimated via combining the consumption level at both baseline and the second resurvey. During a mean follow-up of 10.8 (SD 2.0) years, 29,277 incident cancer cases were recorded among the 510,146 participants who were free of cancer at baseline. Cox regression analyses for incident cancers associated with usual dairy intake were stratified by age-at-risk, sex and region and adjusted for cancer family history, education, income, alcohol intake, smoking, physical activity, soy and fresh fruit intake, and body mass index.

Results
Overall, 20.4% of participants reported consuming dairy products (mainly milk) regularly (i.e. ≥1 day/week), with the estimated mean consumption of 80.8 g/day among regular consumers and of 37.9 g/day among all participants. There were significant positive associations of dairy consumption with risks of total and certain site-specific cancers, with adjusted HRs per 50 g/day usual consumption being 1.07 (95% CI 1.04–1.10), 1.12 (1.02–1.22), 1.19 (1.01–1.41) and 1.17 (1.07–1.29) for total cancer, liver cancer (n = 3191), female breast cancer (n = 2582) and lymphoma (n=915), respectively. However, the association with lymphoma was not statistically significant after correcting for multiple testing. No significant associations were observed for colorectal cancer (n = 3350, 1.08 [1.00–1.17]) or other site-specific cancers.

Conclusion
Among Chinese adults who had relatively lower dairy consumption than Western populations, higher dairy intake was associated with higher risks of liver cancer, female breast cancer and, possibly, lymphoma.