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Study Finds Significant Variation in the Incidence of Nasopharyngeal Cancer Among Ethnic Subgroups of Asian Americans


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Although nasopharyngeal cancer is quite rare in most parts of the world, including the United States, the cancer causes a significant health burden among Asian Americans, which is a fast-growing but understudied racial group. According to the results from a study by Lee et al presented at the virtual 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved, the incidence of nasopharyngeal cancer was over 10 times higher among Chinese Americans and over 14 times higher among Laotian Americans than among non-Hispanic White Americans, with incidence rates surpassing other Asian American subgroups. Future research should explore the environmental, behavioral, and genetic factors that may be contributing to this significantly higher incidence of nasopharyngeal cancer observed in this ethnic subgroup of Asian Americans, according to the study authors.

Study Methodology

The researchers used population-based cancer registry data from the Surveillance, Epidemiology, and End Results Program to identify approximately 9,700 Asian-Americans diagnosed with nasopharyngeal cancer between 1990 and 2014. The researchers divided the population into nine ethnic subgroups: Chinese, Japanese, Filipino, Korean, Asian Indian/Pakistani, Vietnamese, Laotian, Cambodian, and Native Hawaiian/Pacific Islander. After adjusting for age, the researchers calculated the incidence rates of the cancer for each group and compared the rates to the rate for non-Hispanic White patients using incidence rate ratios and 95% confidence intervals. Sex and tumor histology were considered in the analyses as well.

Results

KEY POINTS

  • Chinese Americans and Laotian Americans were over 10 and 14 times more likely to be diagnosed with nasopharyngeal cancer, respectively, than non-Hispanic White Americans, with incidence rates surpassing other Asian American subgroups.
  • The incidence of the undifferentiated nonkeratinizing histology was close to 25 times higher in both Chinese American patients and Laotian American patients compared to non-Hispanic White American patients.

The researchers found that the incidence of nasopharyngeal cancer in all Asian American ethnic subgroups—with the exception of Japanese and Asian Indian/Pakistani patients—were statistically significantly higher than non-Hispanic Whites; most notably, incidence in Laotian Americans was over 14 times higher (incidence rate ratio [IRR] = 14.71, 95% confidence interval [CI] = 11.87–18.02) and incidence in Chinese Americans 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 nonkeratinizing tumors. Relative to non-Hispanic Whites, incidence of the differentiated nonkeratinizing histology was over 30 times higher in Laotian Americans (IRR = 30.19, 95% CI = 17.97–47.45), and the incidence of the undifferentiated non-keratinizing histology was close to 25 times higher in both Chinese American patients and Laotian American patients (IRR = 24.82, 95% CI = 21.97–28.02 and IRR = 24.95, 95% CI = 15.24–38.91, respectively).

“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,” concluded the study authors.

The results from this study may help shift the way cancer risk is studied among people of Asian descent and encourage research into the reasons behind cancer disparities, according to lead author of this study Alice Lee, PhD, MPH, Assistant Professor at California State University, Fullerton.

“Our findings highlight the need to move away from examining cancer among Asian Americans as a single racial group, since there are clear ethnic-specific disparities that are missed with an aggregated approach,” Dr. Lee said in a statement. “By identifying those disproportionately burdened by the disease, we can start thinking about the behavioral, biological, and social factors that may contribute to their higher risk.”

Disclosure: Funding for this study was provided by California State University, Fullerton. The study authors declared no conflicts of interest.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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