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

[BACKGROUND] 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.

[PATIENTS AND METHODS] 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.

[RESULTS] 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.

[CONCLUSIONS] 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.