Risk factors for colorectal cancer in Korea: A population-based retrospective cohort study

Purpose: The incidence of colorectal cancer in Korea has recently increased, making it the second most common cancer in men and the third most common cancer in women. Risk factors for colorectal cancer have been studied worldwide, but risk factors specific for the Korean population have not been established. In this study, we investigated incidence trends and risk factors of colorectal cancer in Korea. Methods: A total of 8,846,749 subjects were included. Colorectal cancer incidence was investigated using Korea National Health Insurance Service claim data from 2004 to 2014. Colorectal cancer diagnoses were obtained by evaluating colorectal cancer diagnostic codes and the cancer registry for cost sharing. Risk factor identification for colorectal cancer was obtained from National Health Examination data from 2004 to 2005. Cox proportional hazard model statistical analysis was used to determine risk factors of colorectal cancer. Results: The incidence of colorectal cancer gradually increased from 2006 to 2014 (from 45.4/100,000 to 54.5/100,000). There was a predominance among men (1.47:1), but incidence trends were similar in both sexes. Old age, high body mass index, and no history of colonoscopy were identified as risk factors in both sexes. High fasting blood glucose, familial history of cancer, frequent alcohol intake, and current smoker were identified as risk factors, especially in men. Conclusion: The incidence of colorectal cancer has been increasing in Korea. Colonoscopy screening was a protective factor for colorectal cancer, and active use of colonoscopy may reduce incidence. Early diagnosis and care are important, particularly for the high-risk group.