Gastric cancer outcomes in adolescents and young adults in Alberta, Canada.

Abstract

e16032 Background: Gastric cancer (GC) poses a significant challenge in Canada, with survival rates at 29%. Adolescents and Young Adults (AYA, ages 18-49) account for about 10% of GC cases but face challenges due to limited treatment guidelines. The biological behaviour of GC differs in younger patients compared with older adults. Understanding these disparities is crucial for developing targeted interventions for this vulnerable population. This study aimed to characterize GC outcomes in AYA patients compared to non-AYA patients in Alberta, Canada. Methods: We used the Alberta Cancer Registry to identify patients diagnosed with primary gastric or gastro-esophageal junction (GEJ) cancer from 2008 to 2023, ensuring a minimum of two years of follow-up. Patients with multiple malignancies or missing staging information were excluded. Those under 50 were classified as AYA (n = 345), while those 50 and older were categorized as non-AYA (n = 2888). We further stratified patients into four groups: early-stage AYA (n = 125), early-stage non-AYA (n = 1200), advanced-stage AYA (n = 220), and advanced-stage non-AYA (n = 1688). Key demographics and clinical variables (sex, gastric region, histology, treatments offered, overall survival (OS)) were compared. Results: In the early-stage cohort, histologic differences emerged, with signet ring cell histology more prevalent in AYA patients (23.2% vs. 10.6%; p < 0.001). AYA patients were also more likely to receive curative-intent systemic therapy (68.0% vs. 55.0%; p = 0.005). In the advanced setting, signet ring cell histology was again more prevalent in AYA patients (27.7% vs. 11.8%; p < 0.001). They were more likely to receive palliative therapy (53.2% vs. 37.4%; p < 0.001) and immunotherapy/chemotherapy combinations (17.1% vs. 11.4%; p = 0.042). Among those starting systemic therapy, more AYA patients progressed to second-line treatment (21.8% vs. 15.2%; p = 0.011). Conclusions: AYA patients with gastric cancer in Alberta exhibit aggressive disease characteristics and receive extensive treatment in both early and advanced stages. However, while outcomes are better in the early stages, they deteriorate in advanced stages despite high rates of second-line treatment, resulting in poorer survival rates for those undergoing systemic treatment in the metastatic setting. This highlights the urgent need for age-specific diagnostic strategies along with comprehensive, age-appropriate supportive care tailored to their distinct clinical and psychosocial needs.