Abstract PO-198: Disparities in nasopharyngeal cancer incidence among Asian American ethnic subgroups
Authors: Lee Alice W. , Sou Angela , Liu Lihua 
Published: January 2022

Abstract
Background: Although nasopharyngeal cancer is a relatively rare malignancy in the United States (U.S.), its racial disparities are striking. Incidence has been shown to be over four times higher in Asian Americans than the general U.S. population and over seven times higher when compared to Whites. However, Asian Americans constitute a heterogeneous racial group, and it is becoming increasingly evident that considering each Asian ethnicity separately is crucial when it comes to cancer research so ethnic-specific differences are not missed. These differences can inform disease etiology and improve prevention efforts, but there is limited literature that considers the diversity of the Asian American population when it comes to nasopharyngeal cancer. Methods: Using population-based cancer registry data in the Surveillance, Epidemiology, and End Results Program from 1990 to 2014, we calculated age-adjusted incidence rates of nasopharyngeal cancer for nine Asian American ethnic subgroups: Chinese, Japanese, Filipino, Korean, Asian Indian/Pakistani, Vietnamese, Laotian, Cambodian, and Native Hawaiian/Pacific Islander. We compared these rates to the rate for non-Hispanic whites using incidence rate ratios (IRRs) and 95% confidence intervals (CIs). Sex and tumor histology were considered in the analyses as well. Results: Approximately 9,700 nasopharyngeal cancer cases were included. Incidence of nasopharyngeal cancer in all Asian American ethnic subgroups with the exception of Japanese and Asian Indian/Pakistani were statistically significantly higher than non-Hispanic whites; most notably, incidence in Laotians was over 14 times higher (IRR=14.71, 95% CI 11.87-18.02) and incidence in Chinese was over 10 times higher (IRR=10.73, 95% CI 10.19-11.29). When tumor histology was considered, the disparities were most pronounced for the differentiated and undifferentiated non-keratinizing tumors. Relative to non-Hispanic whites, incidence of the differentiated non-keratinizing histology was over 30 times higher in Laotians (IRR=30.19, 95% CI 17.97-47.45), and incidence of the undifferentiated non-keratinizing histology was close to 25 times higher in both Chinese and Laotians (IRR=24.82, 95% CI 21.97-28.02 and IRR=24.95, 95% CI 15.24-38.91, respectively). Conclusions: The higher incidence of nasopharyngeal cancer previously observed in Asian Americans is largely attributable to specific ethnic subgroups. Such disparities are overlooked when Asian Americans are studied in the aggregate. Future research should explore the environmental, behavioral, and genetic factors that may contribute to the significantly higher incidence of nasopharyngeal cancer observed in Chinese and Laotians.
Citation Format: Alice W. Lee, Angela Sou, Lihua Liu. Disparities in nasopharyngeal cancer incidence among Asian American ethnic subgroups [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-198.