LAUSR

Background The incidence of gastric cancer is decreasing worldwide, but little is known about how the incidence of different types of gastric adenocarcinoma (GAC), such as non-cardia and cardia subsites, or intestinal and diffuse histotypes, have been changing over time. This study explores the incidence of GAC stratified by anatomic site and histotype in the community in Italy. Methods A multicentre, retrospective, observational study was performed to identify all cases of GAC diagnosed in the community of Bologna and province over a twelve year period from 2001 to 2012. All histological reports of new cases of GAC diagnosed in the study period in the four hospitals of Bologna and province were identified. First histological diagnoses only were included, based on endoscopic biopsies or surgical specimens. Patients resident outside of the region were excluded. The anatomic site (non-cardia or cardia) and the histotype (intestinal or diffuse) were identified. Directly age-standardised incidence rates per year per 100,000 adults were calculated for males and females using the European standard population. Results A total of 2,895 cases of GAC were identified. The majority were non-cardia (2,510; 87%), and were either intestinal (1,409; 49%) or diffuse (972; 34%) histotypes. More cases were seen in males (1,673; 58%) than in females (1,222; 42%). For all GAC, incidence rates decreased from 2001 to 2012 in both males [from 50.0 (95% CI 42.6–57.3) to 28.8 (95% CI 23.5–34.0)] and females [from 24.3 (95% CI 19.9–28.7) to 16.6 (95% CI 13.1–20.1)]. A similar pattern was seen for non-cardia GAC, but not for cardia GAC, whose incidence rates remained stable over time. Incidence rates of intestinal type GAC decreased substantially in males [from 26.8 (95% CI 21.4–32.2) to 16.2 (95% CI 12.3–20.1)] and, to a lesser extent, in females [from 9.1 (95% CI 6.5–11.8) to 5.2 (95% CI 3.3–7.1)]. Incidence rates of diffuse type GAC also decreased in males [from 14.8 (95% CI 10.7–18.8) to 6.9 (95% CI 4.4–9.5)], but less so in females [from 10.4 (95% CI 7.3–13.4) to 8.1 (95% CI 5.6–10.7)]. Conclusion Incidence rates of GAC are decreasing over time in this community in Italy for both males and females. The decline seems to be limited to non-cardia GAC, the intestinal histotype and predominantly to males for the diffuse histotype. Unmeasured risk factors such as H. pylori infection and diet may contribute to the differences. These data yield important information to aid healthcare planning in the region.