Splenic Enlargement During Neoadjuvant Chemotherapy for Gastric Cancer: Treatment-Related Phenomenon or Prognostic Biomarker?

Introduction: Spleen volume (SV) may increase during systemic chemotherapy, potentially reflecting treatment-related hepatic, hematological, and immune alterations. However, the clinical significance of SV changes during neoadjuvant chemotherapy (NAC) for gastric cancer remains unclear. This study evaluated SV changes during NAC and their associations with radiological response and overall survival (OS). Methods: This retrospective cohort study included 111 patients with gastric adenocarcinoma who received NAC followed by curative-intent gastrectomy. SV was measured on computed tomography before and after NAC using semiautomated volumetric segmentation. Relative SV change (ΔSV%) was calculated. Radiological response was assessed according to RECIST 1.1. Associations of ΔSV% with objective response and OS were evaluated using logistic and Cox regression analyses, respectively. Results: Mean SV increased significantly from 250.59 ± 98.11 to 335.40 ± 126.81 cm3 (p < 0.001), with a mean ΔSV% of 34.53 ± 15.72%. SV increased in 108 patients (97.3%). Objective response was observed in 56 patients (50.5%). ΔSV% did not differ between responders and nonresponders (34.05 ± 15.66% vs. 35.03 ± 15.90%; p = 0.730) and was not associated with objective response after multivariable adjustment (OR per 10% increase, 0.932; 95% CI, 0.715–1.207; p = 0.578). ΔSV% was also not associated with OS (adjusted HR, 1.031; 95% CI, 0.859–1.236; p = 0.745). Conclusions: SV increased markedly in nearly all patients during NAC for gastric cancer. However, the magnitude of this increase was not associated with radiological response or OS, suggesting that splenic enlargement during NAC may represent a treatment-associated phenomenon rather than a marker of antitumor efficacy or prognosis.