UCSF

Background & aims

Gastric cancer (GC) remains a leading cause of cancer and cancer-related mortality. Recent reports suggest noncardia GC is increasing in certain U.S.

Populations

However, whether these trends are driven by gastric adenocarcinoma (GA) or other histologies, including neuroendocrine tumors (NETs), lymphoma, or gastrointestinal stromal tumors (GISTs), is unclear.

Methods

We analyzed the Surveillance, Epidemiology and End Results-18 cancer registry (2000-2018) to determine age-standardized incidence rates (ASIR) and annual percentage change (APC) trends for histologically-confirmed GCs, stratified by anatomic location (noncardia vs cardia), age group (20-49 vs 50+ years), sex, race, and ethnicity. Joinpoint regression modeling estimated the statistical significance of trend comparisons.

Results

Of 74,520 individuals with noncardia GC, most (66.2%) were GA, with the next largest categories being non-mucosa-associated lymphoid tissue (non-MALT) lymphomas (6.9%), GIST (6.7%), NET (6.4%), and MALT lymphoma (5.6%). Noncardia GA ASIR was significantly higher than other histologies and demonstrated the greatest differences by race and ethnicity. APCs for GA and MALT, both Helicobacter pylori-associated cancers, declined significantly over time, which was driven primarily by trends among individuals ≥50 years-old. NET and GIST APCs significantly increased irrespective of age group, with the highest APCs observed among non-Hispanic white individuals. Cardia GC was rarer than noncardia GC and comprised primarily by GA (87.9%). Cardia GC incidence fell during the study period, which was primarily driven by decline in cardia GA.

Conclusions

GA was the most common histology. On the basis of our findings, the rise in noncardia GC among certain U.S. populations appears predominantly driven by NET and GIST, not GA. Further studies are needed to clarify underlying etiologies for these findings.