Is young-onset esophageal adenocarcinoma increasing in Japan? An analysis of population-based cancer registries

Abstract

Background: While esophageal squamous cell carcinoma (ESCC) is the predominant histological type in Japan, concern has been expressed over an increase in the proportion of esophageal adenocarcinoma (EAC), especially in middle-aged populations. This study aimed to assess long-term trends in esophageal cancer incidence by histological type. Methods: We used data from three population-based cancer registries in Japan with 10,642 esophageal cancer cases diagnosed between 1993 and 2014. The multiple imputation approach was used to impute a specific histological type (ESCC, EAC, and others) for cases with “Unknown” or missing status. We calculated the age-standardized incidence rates by histological type from 1993 to 2014 and fitted age-period-cohort models to estimate the annual percent changes (APCs) and adjusted incidence rate ratios (IRRs). Results: After imputation of missing data, the largest mean APC increase was seen in the incidence of EAC in men aged 40–49 years (7.1%) followed by those aged 50–59 years (5.5%). The age-period-cohort analysis showed that men who were born in the 1960s and later were more likely to develop EAC relative to men who were born in 1950–1959 (1960–1969 cohort, IRR: 1.42; 1970–1974 cohort, IRR: 2.23), with a period effect indicating a constant increase after 2003. For women, no significant trend in EAC incidence was observed. Conclusions: The incidence of EAC has increased more prominently compared with that of ESCC, especially in men aged 40–59 years, suggesting the impact of increasing obesity in men and a reduction in H. pylori prevalence in Japan.