The Impact of Nativity on Cardia (CAR) Versus Non-Cardia (NCAR) Gastric Cancer Incidence and Survival in Asian Subgroups

Abstract

Introduction: Gastric cancer (GC) is a leading cause of cancer-related deaths worldwide. However, the incidence and survival trends among patients with GC vary by anatomic site of the tumor (cardia (CAR) vs. non-cardia (NCAR)) and race/ethnicity of the patient. While Asians have the highest rates of GC compared to other racial groups in the US, whether these trends are seen among both CAR and NCAR cancers, whether all Asian subgroups are equally affected, and whether nativity (place of birth) additionally impacts GC incidence is not clear. Methods: Using population based cancer data from California Cancer Registry, we retrospectively analyzed Asian patients with GC in California from 1988-2004. We sub-categorized Asian patients into six racial subgroups. We further sub-stratified our analyses by nativity [U.S. born vs foreign born (FB)] and CAR vs NCAR. Cancer incidence was age-adjusted to year 2000 population. Overall survival outcomes were evaluated using Kaplan Meier methods and log rank testing. Results: Overall, there were 6,632 Asian patients with GC, among which 16.0% were US born (USB) and 83.9% were FB, and 87% were NCAR and 13% were CAR. For all Asian subgroups, NCAR had a higher incidence compared to CAR (7.8 vs 1.1 per 100,000/yr, p < 0.01). Among USB patients with NCAR, Japanese patients had higher incidence (10.8 per 100,000/yr). Among FB patients with NCAR, Koreans had the highest incidence followed by the Japanese (30.1 vs 22.8 per 100,000/yr, p < 0.01). Japanese had the highest incidence of CAR in both USB and FB (2.5 and 3.2 per 100,000/yr). CAR incidence was higher among USB than FB patients (2.1 vs 1.5 per 100,000/yr, p=0.009). Overall, 5-year survival for CAR was poorer than NCAR (18.7% vs 27.2%, p < 0.01), and these survival trends were seen among both FB and USB patients. Multivariate Cox proportional hazard models demonstrated poorer survival in CAR compared to NCAR (HR 1.27 95% CI 1.02-1.58, p=0.001). There was no significant difference in survival in FB patients when compared to USB patients (HR, 0.997; 95% CI, 0.81-1.22, p=0.98). Conclusion: There exist significant disparities by Asian subgroups, patient nativity, and anatomic site of the tumor. The highest GC incidence was seen in Japanese, and FB patients had consistently higher cancer incidence. CAR incidence was higher in USB patients. While no significant difference in survival was observed between U.S. Born and FB Asian patients, patients with CAR had significantly lower survival than patients with NCAR.