Preoperative Anemia, Transfusion, and Long-Term Oncologic Outcomes after Gastrectomy: Findings from the POWER4 Cohort

Preoperative anemia and transfusion are common in gastric cancer surgery and have been associated with adverse short-term outcomes. Their impact on long-term oncologic prognosis remains unclear. We aimed to assess the association between preoperative anemia, perioperative red blood cell transfusion, and disease-free survival (DFS) after gastrectomy.

This was a prespecified long-term analysis of the prospective POWER4 multicenter cohort conducted across 72 Spanish hospitals. Patients undergoing elective gastrectomy for gastric cancer between 2019 and 2020 were followed for ≥ 36 months. DFS was defined as time from surgery to recurrence or death. Primary exposures were preoperative anemia (World Health Organization criteria) and perioperative transfusion (within 72 h). Analyses included Kaplan-Meier estimates, multivariable Cox regression, logistic regression for delayed or omitted adjuvant chemotherapy (RIOT), and causal mediation analysis. Generalized additive models (GAMs) explored nonlinear associations between hemoglobin and DFS.

Among 386 patients, 47% had anemia and 28% received transfusion. In 368 with complete follow-up, DFS event rates ranged from 13% (no anemia/no transfusion) to 38% (anemia + transfusion) (p < 0.001). Both exposures were associated with DFS in univariable models but lost significance after adjustment. No hemoglobin threshold was identified. Among 149 eligible patients, RIOT was delayed or omitted in 41%, with neither exposure as independent predictors. Mediation analysis suggested transfusion explained 26% of the effect of anemia on DFS, though not significantly.

Anemia and transfusion were associated with adverse unadjusted outcomes, but not independently. This supports interpreting anemia as a marker of vulnerability rather than a modifiable risk factor for recurrence.