An age-period-cohort analysis of obesity and incident esophageal adenocarcinoma among white males.

The incidence of esophageal adenocarcinoma (EAC) has increased in recent decades. Increases in incidence have been attributed to changes in the prevalence of risk factors for EAC; however, the extent to which these changes explain increases in EAC incidence has not been studied in detail. We used age-period-cohort analysis to estimate changes in the incidence of EAC among white males by age, time period, and birth cohort. Incidence rates per 100,000 individuals were analyzed from 1973 to 2012. Hierarchical Poisson models were used to estimate age, period, and cohort effects, whereby age-specific incidence rates were nested within periods and cohorts. The prevalence of obesity for each time period and birth cohort was included in the model as a fixed-effect. Incidence increased with advancing age (β = 0.12, P < 0.01). There were significant period and birth cohort effects, although the period effect was much larger than the cohort effect. The period effect decreased dramatically when obesity was included as a fixed effect, while the small cohort effect remained unchanged. Results suggest much of the increase in the incidence of EAC can be attributed to a period effect, which may be due to changes in the prevalence of obesity over time.