Recent Decrease in Colorectal Cancer Mortality Rate is Affected by Birth Cohort in Korea

BACKGROUND: Colorectal cancer mortality has started to decrease in several developed countries in Asia. The current study aimed to present the long-term trends in colorectal cancer mortality in Korea using joinpoint analysis and age-period-cohort modeling. MATERIALS AND METHODS: The number of colorectal cancer deaths and the population for each 5-year age group were obtained from Statistics Korea for the period 1984-2013 for adults 30 years and older. Joinpoint regression analysis was conducted to determine changes in trends in age-standardized mortality rates, and age-period-cohort analysis was performed to describe trends in colorectal cancer mortality using the intrinsic estimator method. RESULTS: In men, the age-standardized mortality rate for colorectal cancer increased from 1984 to 2003, and the mortality rates stabilized thereafter, whereas the mortality rate of colorectal cancer in women has decreased since 2004. The age-specific mortality rate of colorectal cancer increased in both men and women over time, whereas decreases in the age-specific mortality rate in younger cohorts were observed. In the age-period-cohort analysis, old age and recent period were associated with higher mortality for both men and women. The birth cohort born after 1919 showed reduced colorectal cancer mortality in both men and women. CONCLUSIONS: Our study showed a recent decreasing trend in colorectal cancer mortality in women and a stable trend in men after 2003-2004. These changes in colorectal cancer mortality may be attributed to birth cohort effects.