Introduction The aim of this study was to evaluate the risk of socioeconomic status (SES) and smoking on cancer mortality and incidence in a large cohort of health examinee.

Methods We evaluated data on 512 713 Korean people who had undergone the biannual health examination, organised by National Health Insurance Corporation, aged over 20 at baseline examination. Subjects were classified into four groups according to their amount of health insurance bill, which imposed in proportion to salary or income. All subjects were followed up from baseline examination (2000–2001) until 31 December 2009 using population-based cancer registry and death certification database. A total of 9166 cancer death cases and 27 792 cancer incident cases were identified during follow-up period. Cox proportional hazards model was used to estimate hazard risk (HR) after adjusted age, sex, and smoking status.

Results SES had inverse associations with cancer mortality. The estimated HRs (95% CI) were 0.968 (0.916 to 1.023), 0.939 (0.877 to 0.985), and 0.790 (0.746 to 0.837) in 2^nd–4^th Quartile, respectively. Smoking habits showed higher risk of cancer death (HR: 1.319, 95% CI 1.259 to 1.382) than lower SES, and also showed significant association with cancer incidence (HR: 1.136, 95% CI 1.101 to 1.172). The association between SES and cancer incidence showed positive trend as opposed to cancer mortality. The highest SES group were at greatest risk of cancer incidence (HR: 1.136, 95% CI 1.096 to 1.176), and 2^nd Q and 3^rd Q group were also showed significant higher risk.

Conclusion Impact of SES on the risk of cancer mortality and incidence were showed reversely.