Racial/Ethnic Patterns of Young-Onset Noncardia Gastric Cancer.

Increasing noncardia gastric cancer incidence rates among individuals age younger than 50 years have gained much attention, particularly as causes remain unknown. Using population-based NIH/NCI's Surveillance, Epidemiology, and End Results (SEER) program data from 2007 to 2015, multivariable logistic regression was used to quantify associations between race/ethnicity and clinicodemographic features among young-onset noncardia gastric cancer patients. A total of 2,872 individuals ages 20 to 49 years were diagnosed with primary noncardia gastric cancer. Age at diagnosis, insurance status, anatomic subsite, American Joint Committee on Cancer (AJCC) clinical stage, histologic type, tumor grade, surgery, and county-level smoking prevalence differed by race/ethnicity (all P ≤ 0.003). Compared with non-Hispanic whites, Hispanics were more likely to be diagnosed at younger ages [odds ratio (OR) = 0.97; 95% confidence intervals (CI), 0.95-0.99], on Medicaid/uninsured (OR = 3.83; 95% CI, 2.89-5.08), diagnosed with higher grade tumors (OR = 1.93; 95% CI, 1.32-2.84), and less likely to undergo surgery (OR = 0.62; 95% CI, 0.44-0.88) or to reside in counties with higher smoking prevalence (OR = 0.15; 95% CI, 0.11-0.21) after adjustment for sex, subsite, and histologic type. Asian/Pacific Islanders were more likely to be female (OR = 1.40; 95% CI, 1.04-1.88), and less likely to be diagnosed with metastatic disease (OR = 0.59; 95% CI, 0.37-0.95) or to reside in counties with higher smoking prevalence (OR = 0.13; 95% CI, 0.08-0.19). Approximately two in every five patients with young-onset noncardia gastric cancer are Hispanic. Further investigation into the molecular heterogeneity of young-onset noncardia gastric cancers by race/ethnicity to understand etiologies underlying this rising disease epidemic is warranted. This population-based cohort study sheds light that biological and environmental factors may partly underlie race/ethnicity-related differences in young-onset noncardia gastric cancer susceptibility and outcomes. ©2019 American Association for Cancer Research.