Increasing Prevalence of Adenocarcinoma of the Oesophagus and Gastro-Oesophageal Junction: A Study of the Swedish Population Between 1970 and 1997

OBJECTIVE: To see whether there was an increasing incidence of adenocarcinoma of the oesophagus and gastric cardia in the Swedish population. If there is a rising trend and variations in it can be found, could it be explained as a period or cohort phenomenon? The data were also compared with the incidence of squamous cell carcinoma and gastric cancer with the gastric cardia excluded. DESIGN: Retrospective study. SETTING: Sweden. SUBJECTS: Swedish population. MAIN OUTCOME MEASURES: Age standardised incidence for each sex was calculated using the age distribution of the world population as a reference. Age-period-cohort models were fitted to data using Poisson regression to model log incidence rates. RESULTS: For the combined group of adenocarcinoma in the oesophagus and gastric cardia age standardised incidence gradually increased during the study period. The median increase between adjacent five-year intervals was 20% in women and 14% in men. A period effect was evident in men. CONCLUSION: This study shows that the incidence of adenocarcinoma of the oesophagus and gastroesophageal junction is rising for both men and women in the Swedish population. This is explained as a period effect. As well as previously-described risk factors such as gastro-oesophageal reflux, obesity, and smoking, the increasing incidence can be explained as a shift in classification from squamous cell carcinoma to adenocarcinoma after 1985.