The prognostic effect of ethnicity for gastric and esophageal cancer: the population-based experience in British Columbia, Canada
1 Cancer Control Research Program, BC Cancer Agency, Vancouver, Canada
2 Interdisciplinary Oncology Program, University of British Columbia, Vancouver, Canada
3 Medical Oncology, BC Cancer Agency, Vancouver, Canada
4 Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, Canada
5 Department of Medicine, University of British Columbia, Vancouver, Canada
6 School of Population and Public Health, University of British Columbia, Vancouver, Canada
7 Department of Statistics, University of British Columbia, Vancouver, Canada
8 Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, Canada
BMC Cancer 2011, 11:164 doi:10.1186/1471-2407-11-164Published: 9 May 2011
Gastric and esophageal cancers are among the most lethal human malignancies. Their epidemiology is geographically diverse. This study compares the survival of gastric and esophageal cancer patients among several ethnic groups including Chinese, South Asians, Iranians and Others in British Columbia (BC), Canada.
Data were obtained from the population-based BC Cancer Registry for patients diagnosed with invasive esophageal and gastric cancer between 1984 and 2006. The ethnicity of patients was estimated according to their names and categorized as Chinese, South Asian, Iranian or Other. Cox proportional hazards regression analysis was used to estimate the effect of ethnicity adjusted for patient sex and age, disease histology, tumor location, disease stage and treatment.
The survival of gastric cancer patients was significantly different among ethnic groups. Chinese patients showed better survival compared to others in univariate and multivariate analysis. The survival of esophageal cancer 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.
Ethnicity may represent underlying genetic factors. Such factors could influence host-tumor interactions by altering the tumor's etiology and therefore its chance of spreading. Alternatively, genetic factors may 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 provide clues for the future identification of genetic or lifestyle factors that underlie these observations.