Background: Gastric cancer is the fourth most common malignancy in the world and the second leading cause of cancer related deaths. Its overall incidence has decreased in recent years, but recent data suggests that its rate has actually been increasing specifically amongst younger adults. Emerging data suggests that it is the combination of biological risk factors and environmental triggers that are the cause for this increasing rate. There has been increased interest in studying early onset gastric cancer (EOGC) as a proxy for understanding the genetic alterations that lead to gastric cancer at any age. However, understanding the environmental factors that lead to the development of cancer at a younger age is an area of study that requires more exploration. In this study, we investigate the epidemiology, environmental risk factors and common presenting symptoms associated with early onset gastric cancer patients. Methods: This is a retrospective cohort study of 174 patients with newly diagnosed gastric adenocarcinoma at three safety net hospitals in Los Angeles between 2010 and 2022. The patients were divided into two groups, with an age cutoff of 45 years old for early onset gastric cancer. We compared the rates of smoking, alcohol use, infection with H pylori and gender between the two groups. The stage at time of presentation, rates of misdiagnosis, presenting symptoms, and mortality rates were also compared. Results: There was no statistically significant difference (p < 0.05) in rates of smoking, alcohol use, and H. pylori infection between the groups. However, patients with early onset gastric cancer were 10% more likely to be misdiagnosed, and 6% more likely to present with metastatic disease. They were also 16% more likely to be female, 17% more likely to be Hispanic, and 22% more likely to expire compared to patients older than 45. An analysis conducted on patients’ presenting symptoms indicated that hematemesis was much more likely to be associated with patients less than 45 to a statistically significant level (p = 0.035). Conclusions: Based on our findings, EOGC was more likely to be seen in females and Hispanic populations. Additionally, no risk factors were identified to be more closely associated with either cohort. EOGC patients were more likely to be misdiagnosed and therefore present with advanced disease, leading to higher rates of mortality. Further investigation into both genetic alterations and environmental factors associated with early onset gastric cancer is warranted, as this holds important implications for patients regarding diagnosis, treatment, and overall outcomes.