Mortality Trends in Colorectal Cancer and Breast Cancer in Korea: Birth Cohort Effects?

Purpose: Cancer has been the leading cause of deaths since 1980s in Korea. Among them, colorectal cancer and breast cancer shows steadily increasing pattern, being the fourth and the fifth common site of cancer death in Korea, respectively. This analysis aimed to evaluate potential contribution of birth cohort effects to the recent increases in mortality of colorectal cancer and breast cancer since 1983 in Korea. Methods: Mortality statistics on deaths of both cancers for the past 20 years of 1983 similar to 2002 were obtained from the National Statistical Office. The age-standardized mortality rates were calculated based on the census population of 1992 as a standard. Results: Age-standardized mortality rate for colorectal cancer increased 4.7-fold in men and 3.6-fold in women, whereas 2.1-fold increase in breast cancer mortality during 1983 similar to 2002. Age-specific mortality rates for colorectal cancer were steadily increasing by age before 1991 in both genders. However, the mortality rates showed an exponentially increasing pattern for the age group of 70 and over during 1993 similar to 2001, which was more prominent in female. The birth cohort curves showed that there were 2- to 3-fold increases in the mortality rates of people who were born in 1931 for colorectal cancer compared to those of people who were born in 1921. Differences in mortality for breast cancer by birth cohort were 1.7-fold among age group of 45 similar to 49 and 50 similar to 54 between 1936 and 1946. Conclusions: This analysis suggests that recent increases in mortality of colorectal cancer and breast cancer could potentially be due to birth cohort effects, i.e. rapid changes in life-style in younger generation. The quantitative approach using age-period-cohort model should be pursued.