Background: The incidence of gastric cancer while declining in many places worldwide is characterized by considerable geographic variability in incidence rates and temporal trends. The United States has large racial, ethnic, and regional variation; we collected data from all 50 states to better characterize recent changes in gastric cancer incidence in the entire United States.

Methods: We extracted data on the annual gastric cancer (ICD-O-3: C16.0-C16.9) incidence rates for the period 1999-2013 from the United Stated Cancer Statistics (USCS) registry, which covers 97% of the population. Both age-adjusted incidence rates and temporal trends of gastric cancer incidence were examined overall, as well as stratified by sociodemographic factors and at the state level. We used Joinpoint regression analysis to compute annual percent change (APC) and average annual percent change (AAPC) and corresponding 95% CIs. Heat maps were created to highlight the temporal trend in age-adjusted incidence rates in each state over three 5-year periods: 1999-2003, 2004-2008, and 2009-2013. As a secondary analysis, we also extracted data from the SEER 13 registries to examine the incidence rates and trends separately for cardia and non-cardia gastric cancers.

Results: Overall gastric cancer incidence decreased from 7.64 per 100,000 in 1999 to 6.55 per 100,000 in 2013, decreasing by 1.02% (AAPC=-1.02; 95% CI, -1.28 to -0.76) annually between 1999 and 2013. However, while overall gastric cancer incidence rates decreased (1999-2008 APC=-1.75, 95% CI, -2.02 to -1.47) and then plateaued (2008-2013 APC=-0.24, 95% CI: -0.89, 0.42) among persons aged ≥50 years, the rates increased among persons aged<50 years (AAPC=0.89, 95% CI: 0.61 to 1.16). Most notable increases were observed among non-Hispanic white females (AAPC=1.46, 95% CI: 0.87 to 2.06) and Hispanic females (AAPC=0.47, 95% CI: 0.10 to 0.84). Based on the analysis of SEER 13 registries, the decreasing trend among persons aged ≥50 years is mainly due to decreasing incidence of non-cardia gastric cancer (AAPC=-2.20,

95% CI, -2.51 to -1.90). Increasing rate of non-cardia cancer helped explain the uprising trend of gastric cancer among aged <50 years (AAPC=0.69, 95% CI: -0.06 to 1.44). States with rapid increase of high risk population groups such as Hispanic females including California and Texas are among the top 5 states with both overall high incidence rate of gastric cancer (1999-2013) and high AAPC (California: 1.77, 95% CI, 0.52 to 2.34; Texas: 1.70, 95% CI, 0.25 to 3.17) within last 5 years (2009-2013) among females aged <50 years.

Conclusions: While gastric cancer, particularly non-cardia, rates have decreased rapidly among persons aged ≥50 years in the United States, the incidence rates among persons aged <50 years have increased. Future studies on explanatory factors for this trend are warranted.

Citation Format: Zhensheng Wang, Anam Khan, Maya Balakrishnan, Hashem B. El-Serag, Aaron P. Thrift. Incidence of gastric cancer in the United States during 1999 to 2013: A 50-state analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1190.