Abstract Body fatness has been associated with several cancers in developed countries, but little is known in China. The purpose of this study was to examine the association between body fatness and cancer incidence, with different anthropometric measures, and compare their predicting values. Between June 2004 and July 2008, the China Kadoorie Biobank (CKB) study recruited 0.5 million adults aged 30-79 years from 10 geographically diverse areas across China, and followed up until December, 2015. Body-mass index (BMI), body fat percentage (BFP), waist circumference (WC), and waist-to-hip ratio (WHR) were measured at baseline. Cox regression yielded adjusted hazard ratios (HRs) associating incidence of all cancers and 15 site-specific cancers with different anthropometric measures, adjusting for education level, marital status, annual household income, alcohol consumption, smoking status and physical activity, and stratifying by age at risk, sex, and region. We compared the ability of cancer risk prediction between different anthropometric measures through a receiver operating characteristic (ROC) analysis. Among 508,362 participants, the overall mean (SD) BMI was 23.66 (3.38) kg/m2, 31.11% of men and 34.24% of women were overweight or obesity (BMI≥25.0kg/m2), and 4.41% of men and 4.26% of women were underweight (BMI<18.5kg/m2). 21,474 incident cancers were identified over an average of 8.94 years of follow-up. Each 5 kg/m2 increase in BMI was associated with an increased risk of endometrial (HR, 2.01; 95% CI, 1.72 to 2.35), postmenopausal breast (HR, 1.29; 95% CI, 1.18 to 1.40), colorectal (HR, 1.17; 95% CI, 1.10 to 1.25) and cervical (HR, 1.15; 95% CI, 1.03 to1.29) cancer, whereas it was associated with a reduced risk of oesophageal (HR, 0.73; 95% CI, 0.67 to 0.79), lung (HR, 0.78; 95% CI, 0.74 to 0.82), liver (HR, 0.85; 95% CI, 0.79 to 0.92), and stomach (HR, 0.88; 95% CI, 0.82 to 0.94) cancer. BMI was the best risk prediction measure for postmenopausal breast and endometrial cancer, whereas BFP were the best for oesophageal, lung, liver and stomach cancer, and WC and WHR did for colorectal cancer. BMI is related to the incidence of several cancers in China. Obesity and overweight, as well as underweight, contribute to the cancer incidence in China. Other anthropometric measures may add information for cancer-specific risk prediction. Citation Format: Lu Wang, Guangfu Jin, Canqing Yu, Jun Lv, Yu Guo, Zheng Bian, Ling Yang, Yiping Chen, Zhibin Hu, Feng Chen, Zhengming Chen, Liming Li, Hongbing Shen. Cancer incidence in relation to body fatness in China: Evidence from a large population-based cohort study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5259.