Objective
Gastric Cancer (GC) is the 4^th most common cancer worldwide. Our prior analysis has shown geographic differences in mortality outcomes. The objective of this study was to measure differences in risk-adjusted survival amongst Brazilians with GC compared to Americans using two representative national datasets.
Methods
A retrospective analysis of patients with GC diagnosed between 2004 and 2019 in the National Cancer Database (Americans) and the Registro Hospitalar do Câncer (Brazilians) was performed. We compared differences in presentation treatment, and survival between the two populations. Stage-stratified Kaplan-Meier analysis and multivariable Cox regression adjusted for demographics, histology and treatment were used to assess differences in overall survival.
Results
Data from 207,847 Americans and 35,772 Brazilian patients with Stage I-IV GC were analyzed. Brazilian patients were younger at diagnosis (mean age = 62.1 ± 13.3 vs 66.2 ± 14.1 years, p<0.001), and presented at higher stage of disease (stage III [22.3% vs 19.9%, p<0.001; stage IV [55.9.0% vs 38.6%, p<0.001]).

For patients with stage II and III disease, Brazilians were less likely to receive surgery (58.5% vs 71.7%, p<0.001) or chemotherapy (64.5% vs 68.8%, p<0.001).
Median follow up time was 14.9 months for the entire cohort. For all stages combined, Americans with GC had longer median OS (18.8 months [95%CI: 18.6-19.0] vs 9.8 months [95%CI: 9.7-10.0]). (Figure 1). On multivariable Cox regression (Table 1), Brazilians with GC had a higher risk of death for stage II to stage IV disease (p<0.001), while there was no significant difference in risk of death at stage I.
Conclusion
In this bi-national study, Brazilian patients with GC presented at younger ages and with more advanced disease as compared to American patients. Brazilians had a corresponding greater risk of death and poorer overall survival across all stages of disease, however this disparity only existed for more advanced disease stages. Further research in to identifying the causes of this observed disparity for advanced GC is required.

<b>Table 1: </b>Comparative Survival Analysis Amongst Americans and Brazilians with Stage I-IV Gastric Cancer

Table 1: Comparative Survival Analysis Amongst Americans and Brazilians with Stage I-IV Gastric Cancer

<b>Figure 1: </b>Five-Year Kaplan Meier Survival Curve for Stage I-III Gastric Cancer

Figure 1: Five-Year Kaplan Meier Survival Curve for Stage I-III Gastric Cancer

Kaitlyn Kelly

University of Wisconsin-Madison

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