GSTM1 and anemia: To address the abovementioned critical research gaps, our study undertakes a large-scale, multinational, multicenter investigation with the following three objectives: first, to determine the prevalence of preoperative anemia in cystectomy patients and assess the frequency of Hb optimization interventions; second, to identify risk factors associated with anemia before cystectomy and blood transfusions; and third, to evaluate the relationship between preoperative anemia and both perioperative and long-term survival outcomes, while adjusting for significant confounding factors.