Su1984 Disparate Outcomes of Cardia vs. Non-Cardia Gastric Cancers: Results From a Large Tertiary Care Center From 2000-2012

Abstract

Introduction: Recent studies in the U.S. have reported steadily rising rates of cardia (CAR) gastric cancer, whereas rates of non-cardia (NCAR) gastric cancer have been declining. In addition, racial/ethnic disparities in CAR vs. NCAR gastric cancer exist, with significantly greater proportions of Asians having NCAR sub-types of cancer. Our study aims to evaluate disparate outcomes between CAR vs. NCAR gastric cancer, with a focus on identifying specific risk factors associated with these differences. Methods: Using data from California Pacific Medical Center, a tertiary referral center in northern California, we retrospectively analyzed adult patients with gastric cancer diagnosed from 2000-2012. Anatomic site-specific comparisons (CAR vs. NCAR cancers) were performed using chi-square testing for categorical variables and Student's t-test for continuous variables. Long-term overall survival was evaluated using Kaplan Meier methods and log-rank testing. Overall 1, 3, and 5-year survival between CAR and NCAR cancers were stratified by sex, race/ethnicity, cancer stage, and histologic subtype. Multivariable Cox proportional hazards models were adjusted for age, sex, race/ethnicity, tobacco or alcohol use, cancer stage, treatment received, and anatomic site. Results: Overall, from 2000-2012 there were a total of 587 patients with gastric cancer (68.5% with NCAR and 31.5% with CAR). No significant difference in mean age of diagnosis was observed between NCAR and CAR cancers (69.3 +/0.7 vs. 67.1 +/0.9, p=0.076). While the majority of gastric cancer patients were white, there was significantly greater proportion of Asians in the NCAR cohort (39.3%, n=158). Compared to patients with NCAR cancers, significantly higher rates of tobacco use (35.8% vs. 52.6 %, p<0.001) and alcohol use (28.5% vs. 55.2%, p<0.001) were seen in CAR cancer patients. In addition, patients with NCAR cancers were more likely to be foreign born (79.4% vs. 51.4%, p=0.001). Overall 5-year survival was significantly higher among patients with NCAR cancers compared to CAR cancers (40.6% vs. 33.9%, p<0.001). However, after adjusting for multiple variables in a multivariate Cox proportional hazards model, the survival difference between NCAR and CAR gastric cancers was no longer significant (HR, 1.03; 95% CI, 0.76-1.39, p=0.87). Conclusions: Significant differences in demographics and clinical characteristics existed between NCAR and CAR gastric cancers. These differences may explain the significantly higher survival observed in patients with NCAR vs. CAR cancers. However, after adjusting for these differences in a multivariate regressionmodel, the survival advantage among patients with NCAR cancers was no longer present.