Age and sex interactions in gastric cancer incidence and mortality trends in Korea

The incidence and mortality of gastric cancer have declined rapidly over the past few decades, but reverse trends in the young generation's differential between sexes in some races have been reported in recent years. To investigate whether this divergent trend can be observed in Korea, a country with the highest incidence in the world, age- and sex-specific incidence and mortality trends were evaluated. Gastric cancer incidence data for the years 1999-2010 and mortality data for the years 1983-2012 were obtained from the Korea Central Cancer Registry and National Statistical Office. Annual percentage changes were calculated by age group (20-39, 40-54, 55-69, 70-79) using Joinpoint regression analysis. Furthermore, age-period-cohort analysis was evaluated. Overall age-standardized gastric cancer incidence in adults aged between 20 and 79 was declining at a nonsignificant average annual percentage change (AAPC) of -0.2 % in males and -0.4 % in females in Korea during 1999-2010. Mortality was steeper at a significant rate of -4.3 and -5.9 % in males and females, respectively. However, age-specific analysis revealed a flat (males 0.2 %, 95 % CI -0.5-0.6) or increasing incidence trend (females 1.7 %, 95 % CI 0.9-2.5) in the 40-54 age group. APC analysis confirmed the decreasing incidence and mortality trend mainly by the cohort effect. The differential pattern between males and females in different age groups suggests a possible effect of detection by screening practice or a signal of the change in epidemiological factors in the incidence and mortality of gastric cancer that warrants further studies.