SAN ANTONIO — Substantial heterogeneity in risk for gastric cancer exists among Asian and Pacific Islanders subgroups and individuals in these subgroups seem to exhibit improved survival following gastric cancer diagnosis compared with non-Hispanic whites. Findings were reported at the American College of Gastroenterology 2019 Annual Scientific Meeting held October 25 to 30 in San Antonio, Texas.

Approximately 26,000 new cases of gastric cancer and more than 10,000 related deaths occur annually in the United States. Asian and Pacific Islanders in aggregate are known to be at increased risk for gastric cancers as a result of differences in Helicobacter pylori prevalence, dietary patterns, smoking habits, and other genetic and environmental factors. Moreover, these differences may cause the behavior of gastric cancer to vary among Asian and Pacific Islanders subgroups.

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Huang, et al1,2 investigated all incident cases of gastric cancer diagnosed between 2011and 2014 from the Surveillance, Epidemiology, and End Results Program registries, which incorporate data from individuals living in California and Hawaii. From the incidence registries, records of patients who belonged to several Asian and Pacific Islanders subgroups were identified: Koreans (California and Hawaii), Japanese (California and Hawaii), Chinese (California and Hawaii), Vietnamese (California only), Filipino (California and Hawaii), and Indians (California only) compared with non-Hispanic whites.


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In total, 2132 incident cases of gastric cancer among Asian and Pacific Islanders and 3984 incident cases of gastric cancers among non-Hispanic whites were identified. Differences among subgroups in all-cause mortality following diagnosis was evaluated using Kaplan-Meier statistics and the log-rank test, and a proportional hazard regression model was used to compare subgroups and adjust for differences in age and stage of diagnosis.

The researchers discovered significant differences and substantial heterogeneity in risk for gastric cancer among Asian and Pacific Islander subgroups. In California, Koreans (23.4 per 100,000; 95% CI, 15.8-31.0) and Japanese (21.4 per 100,000; 95% CI, 16.1-26.7) demonstrated high incidence, Chinese (11.0 per 100,000; 95% CI, 10.4-11.6) and Vietnamese (10.3 per 100,000; 95% CI, 7.8-12.8) people demonstrated intermediate incidence, and Filipinos (4.6 per 100,000; 95% CI, 3.4-5.8) and Indians (3.7 per 100,000; 95% CI, 2.9-4.5) demonstrated low incidence.1 In Hawaii, the findings were similar: Koreans (16.3 per 100,000; 95% CI, 11.4-21.2) and Japanese (16.0 per 100,000; 95% CI, 12.5-19.5) demonstrated high incidence, while Filipino (5.0 per 100,000; 95% CI, 3.4- 6.6) and Chinese (4.8 per 100,000; 95% CI, 2.1-7.5) people demonstrated low incidence.1 The incidence among non-Hispanic whites in California was 6.6 (95% CI, 6.0-7.2), whereas in Hawaii it was 4.7 (95% CI, 3.1-6.3).1

Substantial differences in all-cause survival among Asian and Pacific Islander subgroups were also observed. Korean Americans appears to have the best overall survival.2 Part of this difference may be explained by a higher percentage of cancers diagnosed while at a local stage in Koreans (37.8%), while Filipinos had the lowest percentage of early diagnosis (18.9%).2 Furthermore, in multivariable regression adjusted for age, gender, and stage of diagnosis, all Asian and Pacific Islander subgroups, except Filipinos, demonstrated superior survival compared with non-Hispanic whites, suggesting possible underlying biological differences.2

The study authors concluded that the higher risk for gastric cancer in Asian and Pacific Islanders in aggregate is driven by certain subgroups which may hold implications for screening for gastric cancer. In addition, these differences may represent cohort effects from generational migration or environmental and regional dietary differences.

References

1. Huang R, Hwang JH, Palaniappan L. Disaggregation of gastric cancer risk between Asian American subgroups. Presented at: American College of Gastroenterology 2019 Annual Scientific Meeting; October 25-30, 2019; San Antonio, TX. Poster P1767.

2. Huang R, Palaniappan L, Hwang JH. Variability in gastric cancer survival by disaggregated Asian American subgroups. Presented at: American College of Gastroenterology 2019 Annual Scientific Meeting; October 25-30, 2019; San Antonio, TX. Poster P1768.