Completion of perioperative chemotherapy and tumor regression grade as independent predictors of one-year survival after total gastrectomy for gastric cancer: a retrospective cohort study

Gastric cancer remains a major global health burden, with persistently high mortality rates despite advances in multimodal treatment. Total gastrectomy (TG) constitutes a cornerstone of curative therapy; however, the factors governing early postoperative survival remain incompletely characterized. This study aimed to identify clinical and pathological predictors of 1-year overall survival (OS) following curative-intent TG, with particular emphasis on the oncological treatment strategy and tumor regression grade (TRG). We retrospectively analyzed 145 patients who underwent TG between 2012 and 2023, excluding n = 4 adjuvant-only cases. To avoid statistical collinearity, multivariable Cox proportional hazards regression was performed in two sequential steps: Model 1 assessed the treatment strategy across the overall cohort (N = 145), while Model 2 evaluated TRG exclusively within the neoadjuvant-treated subgroup (n = 85). Both models incorporated the lymph node ratio (LNR) and surgical approach, and were adjusted for resection margin status (R-status), comorbidity burden (CCI), and severe postoperative complications (Clavien-Dindo ≥ III). A 60-day landmark analysis was conducted to mitigate immortal time bias. Completion of the perioperative chemotherapy sequence was independently associated with significantly improved 1-year OS compared to neoadjuvant therapy alone (HR = 0.20; 95% CI, 0.08–0.50; p = 0.001). This survival advantage remained highly significant in the 60-day landmark analysis (p = 0.004). Notably, 55.3% of patients who initiated neoadjuvant chemotherapy did not proceed to the adjuvant phase, primarily owing to patient refusal or medical contraindications. When evaluated exclusively within the neoadjuvant-treated subgroup, a poorer TRG demonstrated a prognostic trend toward decreased survival (HR = 1.60; 95% CI, 0.98–2.59; p = 0.059). Although severe complications (CD ≥ III) occurred in 55.9% of patients, their incidence did not differ significantly across treatment groups (p = 0.894) and did not diminish the independent prognostic value of treatment completion. The surgical approach (robotic vs. open) exerted no significant effect on 1-year OS (HR = 0.88; p = 0.745). Completion of the perioperative chemotherapy sequence and a favorable TRG represent two distinct and critical determinants of 1-year survival following TG for gastric cancer. While residual selection bias inherent to retrospective analyses must be acknowledged, the prognostic advantage conferred by treatment completion remains robust after adjustment for surgical morbidity, R-status, and immortal time bias. These findings underscore the prognostic importance of treatment adherence and tumor chemosensitivity, and highlight the need for individualized perioperative management strategies.