Age, period and cohort effects on gastric cancer mortality in Spain, 1980-2021

Background: this study aimed to evaluate the effects of age, time period and cohort (A-P-C) on gastric cancer (GC) mortality in Spain from 1980 to 2021. Methods: an ecological trend study was performed (with aggregated data obtained from the Spanish National Statistics Institute (INE). Joinpoint regression software was used to estimate rates by sex and age group (< 35, 35-64, > 64 years) and mortality trends. The National Cancer Institute A-P-C tools were used to assess the effects of age, time of death and birth cohort. Results: GC mortality rates in Spain decreased significantly in both sexes. In the under-35 age group, rates were stable after an initial significant decline. In the 35-64 age group, the decline was more pronounced in males than in females. In the 65+ age group, rates fell significantly for both sexes, but more so for females than for males. The net drift and local drift also showed significant decreases across all age groups from 24 years onwards. GC mortality rates increased with age and decreased with calendar time and successive birth cohorts, regardless of sex. The ratio of age-specific rates between males and females increased with age, and birth cohort relative risk estimates followed a steady downward trend until the mid-1970s, after which the decline stabilized. The relative risk decreased for both sexes, with a more pronounced decrease in males. Conclusion: GC mortality rates in Spain have been decreasing over time and across successive birth cohorts, with a stabilizing trend observed for those under 35 years of age.