The impact of American Indian and Alaska Native ethnicity on the presentation and surgical treatment of gastric cancer: An NCDB analysis from 2004-2014.

Abstract

13 Background: American Indian/Alaska Natives (AI/ANs) with gastric adenocarcinoma (GC) have an incidence and mortality nearly double that of matched Non-Hispanic Whites (NHW) in historical data sets. However, the impact of AI/AN ethnicity on disease presentation and treatment is underrepresented in gastric cancer epidemiologic studies and has not been evaluated in a contemporary population. Methods: The National Cancer Data Base (NCDB) was queried from 2004-2014 to identify patients with gastric cancer who identify as AI/AN or NHW. Patient demographics, tumor characteristics, and treatment details, including surgical quality metrics, were compared using Chi-square and Student's t-tests. Results: There were 22,286 NHW and 115 AI/AN GC patients with complete staging information. Compared to NHW, AI/ANs were younger (age ≤65) at diagnosis (p < 0.001), which translated to a younger median age at death (NHW:70 years, AI/ANs:60 years, p < 0.001). AI/ANs more often lived over 100 miles from their treatment facility (p < 0.001) in non-metropolitan cities (p < 0.001). Stage distribution was not different for the AI/AN population when compared to the NHW population: 37% vs. 35% Stage I; 33% vs. 37% Stage II; 10% vs. 11% Stage III; and 19% vs. 16% Stage IV (p = NS). However, AI/ANs had a higher rate of signet ring cell histology and linitis plastica (26% vs. 15%, p = 0.002) compared to NHWs. More AI/AN patients compared to NHW patients had delays over eight weeks to initiation of treatment, 19% vs. 11% (p = 0.008). There were no statistically significant differences for surgical quality metrics, including type of surgery, rate of ≥15 lymph nodes retrieved, margin positivity, or 30-day mortality (p = NS). Conclusions: Both biological and social disparities are evident for AI/ANs with gastric cancer. AI/ANs develop and die from gastric cancer at younger ages compared to NHWs and present with higher rates of aggressive histology. They also travel longer distances for treatment and experience greater treatment delays. These features may partly underlie the higher mortality rates previously described.