Background: Gastric and esophageal (GE) cancers most commonly occur in older adults in their 60’s. There are inconsistent reports about prognosis in adolescent and young adult (AYA) pts, and treatment patterns and outcomes in this population have not been well characterized. Methods: A retrospective analysis was performed for AYA (age < 40) pts with GE cancers who presented to Princess Margaret Cancer Centre from 2008 to 2016. The Kaplan-Meier method was used to analyze progression free (PFS) and overall survival (OS). Results: We identified 57 AYA GE cancer pts (30 gastric, 27 esophageal). Features at diagnosis included: median age 35, 51% female (70% in gastric, 30% in esophageal), 82% with performance status 0-1, 83% Charlson Comorbidity Index 0, 54% stage IV. For gastric pts, 53% had diffuse histology and 47% had signet ring adenocarcinoma. There was a negative family history of gastric or esophageal cancer in 77% of pts. Curative intent treatment was used in 23 pts, palliative in 34. In curative pts, 48% had neoadjuvant therapy, 52% had upfront surgery. Of pts who underwent surgery, 57% had T3 or T4a disease and 38% had N2 or N3 disease. Median OS in curative pts was 39.9 months (95% CI 19.7-69.9), with a 5-year OS rate of 37% (95% CI 20-67). Of the palliative pts, 91% had chemotherapy. First line chemotherapy was a triplet regimen in 80%, doublet in 13%. The median number of treatment cycles on first line chemotherapy was 6, with a median PFS of 7.4 months (95% CI 5.4-10.5). At progression, 14 pts had second line treatment, 3 pts had third line and only 1 pt was treated beyond third line. Median OS in palliative pts was 12.1 months (95% CI 8-21.3). Conclusions: Consistent with the literature, our gastric AYA pts had increased female predominance and diffuse histology. Many AYA pts had advanced disease at diagnosis, with over half of pts presenting with metastatic disease. In both the curative and palliative setting, AYA pts did not have better survival outcomes despite being young with few comorbidities, suggesting they may have more aggressive biology.