F or patients with solid tumors, surgery is often the main treatment, but the issue of the potential benefits and risks of red blood cell (RBC) transfusions during surgery remains. Although previous studies have indicated that a restrictive RBC transfusion strategy is as safe and effective as a liberal one, patients with cancer are not included in most such trials. This parallel-group, doubleblind, superiority, randomized controlled trial was undertaken to determine whether a restrictive strategy of RBC transfusion was superior to a liberal one for reducing mortality and severe clinical complications in patients having major oncologic surgery.At the time of intensive care unit (ICU) admission, patients were randomized in a 1:1 ratio to either a restrictive or liberal RBC transfusion strategy. Patients in the restrictive strategy group received 1 RBC unit each time their hemoglobin (Hgb) concentration decreased to less than 7 g/dL; for those in the liberal strategy group, 1 RBC unit was administered when the Hgb concentration decreased to less than 9 g/dL. No additional units were given when the goal Hgb concentration was reached, that is, 7 and 9 g/dL for the respective strategies. The primary outcome was a composite end point of death from all causes or severe clinical complications within 30 days after randomization. Severe clinical complications included major cardiovascular complications, septic shock, acute kidney injury (AKI) requiring renal replacement therapy, acute respiratory distress syndrome, and reoperation. Secondary outcomes were the 30-day incidence of infection, development of AKI, need and duration of mechanical ventilation, duration of vasopressor therapy, ICU readmission, ICU and hospital lengths of stay, and 60-day mortality. Statistical analyses were performed using SPSS version 18.0 (SPSS Inc, Chicago, Ill); 2-sided P < 0.05 indicated statistical significance.Of 1521 patients screened for eligibility, the final cohort included 97 in the liberal group and 101 in the restrictive group. The 2 study groups were balanced in baseline characteristics. Most patients had a good performance status, localized disease, and elective surgery for gastrointestinal cancer. The primary composite end point at 30 days occurred in 19 patients (19.6%) in the liberal group and in 36 patients (35.6%) in the restrictive group (P = 0.012). This is an absolute risk reduction for the liberal strategy of 16% (95% confidence interval, 3.8%-28.2%) and a number needed to treat of 6.2 (95% confidence interval, 3.5-26.5) to avoid the composite outcome. At the 30-day follow-up, 31 patients (15.7%) died, 8 in the liberal group (8.2%) compared with 23 (22.8%) in the restrictive group (P = 0.005). At 60 days, the respective mortality rates were 11.3% and 23.8% (11 and 24 patients, respectively; P = 0.022). At 30 days, fewer patients in the liberal group had major cardiovascular events and a lower incidence of intra-abdominal infection. No difference was seen in the incidence of septic shock, and no statistically significant dif...