Racial and Ethnic Minorities at Increased Risk for Gastric Cancer in a Regional US Population Study.

Background And Aims: Limited data are available on risk factors for gastric cancer in the United States. We aimed to characterize risk for gastric cancer based on race/ethnicity and additional established risk factors.

Methods: We conducted a retrospective cohort study from 2008 to 2014 from an integrated health care system in Southern California to assess incidence of gastric cancer by race/ethnicity. We then conducted an age- and sex-matched case-cohort study to evaluate additional risk factors: Helicobacter pylori infection, tobacco use, family history, obesity, language, and socioeconomic status. Subgroup analysis was performed for language and socioeconomic status by race/ethnicity.

Results: The incidence of gastric cancer in the reference (non-Hispanic white) population was 8.2 (95% confidence interval [CI], 7.7-8.7) cases per 100,000 person-years. Incidence values for Asians, Hispanics, and non-Hispanic black persons were higher: 12.7 (95% CI, 11.1-14.3), 12.7 (95% CI, 11.7-13.7), and 11.8 (95% CI, 10.3-13.2) cases per 100,000 person-years, respectively (all P < .0001). In logistic regression analysis, we found race/ethnicity to be an independent risk factor for gastric cancer; the odds ratio (OR) for non-Hispanic black persons was 1.5 (95% CI, 1.22-1.72; P < .0001), the OR for Hispanics was 1.4 (95% CI, 1.22-1.57; P < .0001), and the OR for Asians was 1.5 (95% CI, 1.28-1.81; P < .0001), compared with the non-Hispanic white population. Other independent risk factors included infection with H pylori (OR, 4.6; 95% CI, 3.8-5.7), smoking history (OR, 1.4; 95% CI, 1.3-1.6), and family history of gastric cancer (OR, 3.4; 95% CI, 2.6-4.4) (all P < .0001). Non-English language was a significant risk factor for gastric cancer in Asians (P = .05). Higher annual median income was associated with reduced risk (OR, 0.84; 95% CI, 0.75-0.95; P = .0004).

Conclusions: In a population study in Southern California, we found racial/ethnic minorities to have a 40%-50% increase in risk of gastric cancer compared with the non-Hispanic white population. In addition to H pylori infection, smoking, family history, and low socioeconomic status were also associated with increased risk. Further characterization of high-risk groups may identify populations appropriate for targeted screening.