Effect of peri-operative blood transfusions on long-term prognosis of patients with colorectal cancer

Background: Patients with colorectal cancer often present with anaemia and require red blood cell transfusions (RBCT) during their peri-operative course. Evidence suggests a significant association between RBCT and poor long-term outcomes in surgical patients, but the findings in colorectal cancer are contradictory. Material and methods: The aim of this retrospective, single-centre, cohort study was to investigate the prognostic role of peri-operative RBCT in a large cohort of patients with stage I-III colorectal cancer submitted to curative surgery between 2005 and 2017. The propensity score matching technique was applied to adjust for potential confounding factors. Results: Among 1,414 patients operated within the study period, 895 fulfilled the inclusion criteria: 29.6% (n=265) received peri-operative RBCT. The group that received peri-operative RBCT was significantly older (p<0.001), had more comorbidities (p<0.001), more advanced tumours (p<0.001) and more colon tumours (p=0.002) and stayed in hospital longer (p<0.001). Post-operative mortality was 7-fold higher (2.3 vs 0.3%, p=0.01) in this group. Survival outcomes were significantly worse in the group receiving RBCT than in the group not receiving RBCT for both overall (64.5 vs 80.1%, p<0.001) and cancer-specific survival (74.3 vs 85.1%, p<0.001). On multivariable analysis, peri-operative RBCT was significantly associated with poorer overall survival (hazard ratio 1.51, p=0.009). When transfused and non-transfused cases were paired through the propensity score matching technique considering main clinico-pathological features, no differences in overall and cancer-specific survival were found. Discussion: Our data suggest that, after adjustment for potential confounding factors, no significant association exists between RBCT and prognosis in colorectal cancer.