Abstract 1377: Generational immigration status and gastric cancer incidence among Japanese descendants: An analysis of the Multiethnic Cohort study.

Abstract Background: Racial and ethnic minorities in the US experience disproportionately higher rates of gastric cancer (GC) compared to the general population. However, the impact of immigration history on these disparities is not well understood. We aimed to evaluate the association between immigration generation and GC risk among Japanese descendants. Methods: We conducted analyses using the population-based Multiethnic Cohort Study (MEC), which enrolled residents of Hawaii and California between 1993 to 1996. Individuals who self-identified as being of Japanese ethnic or racial background were included, excluding those who were born or had parents born in locations other than the US or Japan. Cox proportional hazard models were used to examine the association between immigration generation of Japanese descendants and the risk of GC overall and by anatomical subtype, adjusting for demographic, dietary, and lifestyle variables. Results: Among 94,232 individuals (median age: 61 years; male 47.4%), 716 primary GC cases were identified. The risk of developing GC was higher among all three generations of Japanese descendants compared to non-Hispanic Whites (NHWs). First generation had the highest risk (HR: 4.62, 95%CI 3.24-6.59), followed by the second generation (US-born, with both parents Japan-born; HR: 3.66, 95%CI 2.89-4.64; US-born, with one parent Japan-born, HR: 3.39, 95%CI 2.55-4.50), and the third generation (HR: 2.57, 95%CI 1.93-3.42). The association was strongest among non-cardia GC, with HRs of 5.93, 4.48, and 3.28 for the first, second, and third generations, respectively. Conclusions: GC risk declined across successive generations of Japanese descendants but remained significantly higher than in NHWs. Recognizing and monitoring these persistently high-risk populations may guide targeted screening and inform research into environmental, biological, and transgenerational factors underlying gastric cancer susceptibility. Citation Format: Haejin In, Katherine A. De la Torre-Cisneros, Alexandra Adams, Chunxia Chen, Brijesh Rana, Lynne R. Wilkens, Meira Epplein. Generational immigration status and gastric cancer incidence among Japanese descendants: An analysis of the Multiethnic Cohort study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1377.