Increasing Trend of Colorectal Cancer Incidence in Korea, 1999-2009

PURPOSE This study was conducted in order to demonstrate changing trends in colorectal cancer incidence according to sex, age group, and anatomical location in the Korean population. MATERIALS AND METHODS Data from the Korea Central Cancer Registry between 1999 and 2009 were analyzed. Annual percent changes (APCs) of sex- and age-specific incidence rates for cancer of the proximal colon (International Statistical Classification of Diseases and Related Health Problems, 10th revision [ICD-10] code C18.0-18.5), distal colon (C18.6-18.7), and rectum (C19-20), and male-to-female incidence rate ratios (IRR) were calculated. RESULTS The age-standardized incidence rate (ASR) of colorectal cancer was 27 (per 100,000) in 1999 and increased to 50.2 in 2009 among men (APC, 6.6%). The ASR for women was 17.2 in 1999 and 26.9 in 2009 (APC, 5.1%). The rectum was the most common site of cancer among both men and women during 1999 and 2009. However, the distal colon had the highest APC (10.8% among men and 8.4% among women), followed by the proximal colon (7.9% among men and 6.6% among women), and rectum (5.2% among men and 2.4% among women). The proportion of rectal cancer decreased from 51.5% in 1999 to 47.1% in 2009 among men, and from 50.5% to 42.8% among women. An increase in the male-to-female IRR was observed for distal colon cancer and rectal cancer, whereas the IRR for proximal colon cancer was stable. CONCLUSION The rapid increase in colorectal cancer incidence is mainly attributed to the increase in colon cancer, especially distal colon cancer, and may be explained by a transition of risk factors for subsites or by the effect of colorectal cancer screening.