Race, Ethnicity, Socioeconomic Status and Site-specific Risk for Gastric Cancer

Differences in gastric cancer risk by race/ethnicity have been reported but data on risk by anatomic subsite are lacking. We assessed site-specific differences in gastric cancer risk according to race/ethnicity and socioeconomic status. Methods: Participants included incident cases of gastric adenocarcinoma age >18 years in the Surveillance Epidemiology and End Results Program 2000–2014. Primary outcome was risk for incident gastric cancer, overall, and by anatomic subsite (cardia vs. non-cardia). Age-adjusted incidence rates were used to estimate adjusted incidence rate ratios (IRR) and their 95% confidence intervals (CI). Risk was assessed by race/ethnicity and neighborhood socioeconomic status (nSES). Results: We identified 77,881 cases of incident gastric cancer (n = 23,651 cardia; n = 35,825 non-cardia; n = 18,405 other). For all gastric cancers, adjusted IRRs (95% CI) were higher for blacks [1.72 (95% CI: 1.68–1.76)], Hispanics [1.77 (1.73–1.80)], and Asian/Pacific Islanders [2.12 (2.08–2.17)] compared to non-Hispanic whites. Opposite trends in risk for cardia vs. non-cardia cancer by race/ethnicity were observed. Compared to non- Hispanic whites, cardia IRRs (95% CI) were 0.55 (0.52–0.59) for blacks, 0.63 (0.60–0.66) for Hispanics, and 0.59 (0.56–0.62) for Asians/Pacific Islanders. Non-cardia IRRs (95% CI) were 2.78 (2.69–2.87) for blacks, 2.83 (2.75- 2.91) for Hispanics, and 3.86 (3.75–3.97) for Asians/Pacific Islanders relative to non-Hispanic whites. Increasing risk with decreasing nSES was observed for all gastric cancers (p trend < 0.0001), with moderate variation for non- cardia cancer but no substantial variation observed for cardia cancer. Conclusions. Gastric cancer incidence varies substantially by race/ethnicity and nSES, but with markedly different associations by anatomic subsite. Non-cardia cancer risk is higher among minorities than non-Hispanic whites and varies only moderately by nSES; while cardia cancer risk is lower among minorities and does not vary by nSES. Unique opportunities for addressing disparities exist for cardia and non-cardia gastric cancer.

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