E0683 - Primary Gastric Cancer Mortality Rates Are Decreasing in Young Men but Not Young Women in the U.S., 2000-2019: A Population-Based Time-Trend Analysis Using the CDC’s National Center of Health Statistics (NCHS) Database

Introduction: Recent data showed that incidence of gastric cancer (GC) has been increasing in the US over the last two decades among younger women (< 55 years) at a significantly greater rate compared to younger men. However, the impact of such findings on mortality has not been evaluated. The aim of this study was to investigate sex and age-specific GC mortality rates in the US using CDC’s National Center of Health Statistics (NCHS) database.

Methods: The NCHS database is a nationally representative database that covers ≈100% of occurred deaths. For this study, deaths attributed to GC in the US during 2000-2019 were included and mortality rates per 100,000 population were calculated using SEER*Stat software (v8.4.0, NCI). Rates were age-adjusted to the 2000 US population and stratified by sex and age of two groups, younger adults (age < 55 years) and older adults (age < ![if !msEquation] >< ![if !vml] >< ![endif] >< ![endif] >55 years). Time trends of mortality rates were estimated using Joinpoint Regression Program (v4.9.0.1, NCI), which utilizes Monte Carlo Permutation analysis to estimate the simplest trend. Annual percentage change (APC) and average APC (AAPC) were calculated. Sex-specific pairwise comparison was conducted for identicalness (test of coincidence) and parallelism (test of parallelism) along with assessing AAPC difference. A two-sided p-value cutoff of 0.05 was utilized.

Results: A total of 230,158 people died of GC during the study period (40.8% women). Overall, GC mortality rates were decreasing in men (AAPC=-2.87, p< 0.001) at a significantly greater rate compared to women (AAPC=-2.34, p< 0.001). Among older adults (195,893 deaths; 40.9% women), GC mortality rates have been decreasing in both men (AAPC=-3,17, p< 0.001) and women (AAPC=-2.89, p< 0.001) without a significant difference. However, among younger adults (34,250 deaths; 40.5% women), GC mortality rates have been decreasing in men (AAPC=-0.97, p< 0.001) but not in women (AAPC=0.01, p=0.93) with an absolute AAPC difference of 0.98 (p< 0.001). The trends were non-identical and non-parallel (both p< 0.001) suggesting that mortality rates among men are decreasing at a significantly greater rate compared to the stable trend among women.

Discussion: Nationwide data from the CDC’s NCHS database showed that mortality rates of GC were overall decreasing. However, among younger adults (aged < 55 years), mortality rates were decreasing in men but not in women. Future studies should elucidate risk factors in this population.