Host Determinants of Adjuvant Chemotherapy Initiation and Survival in Upper Gastrointestinal Adenocarcinoma

Introduction: Perioperative systemic therapy improves outcomes in gastroesophageal adenocarcinoma, but many patients do not receive postoperative treatment. We examined whether host characteristics and perioperative inflammatory and albumin changes provided information about adjuvant initiation beyond tumour pathology, and whether initiation was associated with survival and disease control. Method: This retrospective cohort included patients undergoing curative-intent resection for gastroesophageal adenocarcinoma at the McGill University Health Centre between 2006 and 2025. Sequential logistic models evaluated pathological characteristics, pre-treatment host variables and perioperative changes in CBC-derived neutrophil-to-lymphocyte ratio (cNLR) and albumin. Postoperative measurements preceded adjuvant initiation. Nested comparisons used matched complete cases. Day-90 landmark and time-varying Cox models assessed associations between adjuvant initiation and survival. Results: Among 243 patients, 78 (32.1%) did not initiate adjuvant therapy. Adding host variables improved apparent discrimination for initiation beyond pathology (AUC 0.672 to 0.763; P=0.002). Greater perioperative cNLR increase was associated with lower odds of initiation (adjusted OR 0.67 per unit increase in {Delta}log2; cNLR, 95% CI 0.47-0.95), whereas more favourable albumin change was associated with higher odds (OR 1.07 per g/L, 95% CI 1.01-1.13). Neither marker retained a clear independent association when modelled together. Adjuvant initiation by day 90 was associated with longer overall survival (adjusted HR 0.53, 95% CI 0.36-0.78) and disease-free survival (HR 0.57, 95% CI 0.39-0.84), with similar time-varying findings. Conclusion: Host inflammatory and albumin changes added information about adjuvant initiation beyond tumour pathology, and initiation was associated with longer survival. Prospective evaluation should determine whether host-directed perioperative strategies can improve postoperative treatment delivery.