Background The key components of metabolic syndrome (MS) are waist circumference,blood pressure,fast blood glucose,high density lipoprotein cholesterol (HDL-c) and triglycerides (TG).These components have,separately and jointly,been associated with an increased risk of cardiovascular diseases.In this study,we aimed to explore the association between MS components and cancer risk in a population-based cohort in China.Methods We established a population-based cohort with 17 779 individuals aged 35 and above at baseline in 2004 and 2005 in Changzhou,Jiangsu Province,China.All participants were face-to-face interviewed to complete a questionnaire and were accepted physical examinations including blood tests for glucose and lipids and physical measurements for obesity and blood pressure.In 2009,a total of 16 284 subjects (6886 men and 9398 women,91.6％) attended the flow-up interviews and the participants or their family members reported all the hospitalizations and diseases including cancer occurred during the follow-up period.Multivariate Cox regression was used to estimate the hazard ratios (HRs) of metabolic syndrome components and cancer incidence.Results There was a dose-response association between cancer risk and the number of MS components presented at baseline (P for trend=0.012) and the HR (95％ confidence interval (CI)) was 2.63 (1.27-5.45) for subjects carrying 3 or more metabolic syndrome components after adjustment for possible confounding factors.Specifically,the multivariate-adjusted HRs (95％ CIs) for cancer risk in subjects with central obesity,high fasting glucose,low HDL-c were 1.94 (1.01-3.74),2.04 (1.10-3.77) and 2.05 (1.09-3.88),respectively.Conclusions In this population-based,prospective cohort study in China,we found MS components,e.g.,central obesity,high fasting glucose,low HDL-c were risk factors for cancer development.Early intervention of MS components may be also beneficial to reduce cancer burden.