The Prognostic Effect of Ethnicity for Gastric and Esophageal Cancer: The Population-Based Experience in British Columbia, Canada

Background: Gastric and esophageal cancers are among the most lethal human malignancies. Their epidemiologyis geographically diverse. This study compares the survival of gastric and esophageal cancer patients amongseveral ethnic groups including Chinese, South Asians, Iranians and Others in British Columbia (BC), Canada.Methods: Data were obtained from the population-based BC Cancer Registry for patients diagnosed with invasiveesophageal and gastric cancer between 1984 and 2006. The ethnicity of patients was estimated according to theirnames and categorized as Chinese, South Asian, Iranian or Other. Cox proportional hazards regression analysis wasused to estimate the effect of ethnicity adjusted for patient sex and age, disease histology, tumor location, diseasestage and treatment.Results: The survival of gastric cancer patients was significantly different among ethnic groups. Chinese patientsshowed better survival compared to others in univariate and multivariate analysis. The survival of esophagealcancer patients was significantly different among ethnic groups when the data was analyzed by a univariate test(p = 0.029), but not in the Cox multivariate model adjusted for other patient and prognostic factors.Conclusions: Ethnicity may represent underlying genetic factors. Such factors could influence host-tumorinteractions by altering the tumor’s etiology and therefore its chance of spreading. Alternatively, genetic factorsmay determine response to treatments. Finally, ethnicity may represent non-genetic factors that affect survival.Differences in survival by ethnicity support the importance of ethnicity as a prognostic factor, and may provideclues for the future identification of genetic or lifestyle factors that underlie these observations.