Perioperative blood transfusions and recurrence of colorectal cancer

Abstract

Background: The improvement of renal allograft survival by pre-transplantation transfusions alerted to the potential detrimental effect of transfusions in cancer treatment. Objectives: This meta-analysis evaluates the role of perioperative blood transfusions (PBT) on colorectal cancer recurrence. This is accomplished by updating the results of a previously published meta-analysis (Amato 2006) to December 2009. Search methods: Papers were retrieved using Medline, EMBASE, the Cochrane Library, trials web-based registries, or the CCG Database. The search strategy was: (colon OR rectal OR colorectal) WITH (cancer OR tumor OR neoplasm) AND transfusion. The publication bias was balanced by reviewing the proceedings of international congresses. Selection criteria: Patients undergoing curative resection of colorectal cancer (classified either as Dukes stages A-C, Astler-Coller stages A-C2, or TNM stages T1-3a/N0-1/M0) were included if they had received blood products within one month of surgery. Excluded were patients with distant metastases and studies with short follow-up or no data. Data collection and analysis: A specific form was used for data collection. Data was cross-checked, using the most recent publication in case of repetitive ones. Papers' quality was evaluated using the method by Evans and Pollock. Odds ratios (OR, with 95% confidence intervals) were computed for each study, and pooled estimates were generated by RevMan (version 5). When available, data were stratified for risk factors of cancer recurrence. Main results: Updating the previous review through December 2009 identified 41 additional papers, for a grand total of 278 references. Two-hundred and fourty-two of them were excluded because they analyzed survival (n=27), were repetitive (n=29), letters/reviews (n=71) or had no data (n=115). Thirty-six studies on 12,127 patients remained included: 23 showed a detrimental effect of PBT; 22 used multivariable analyses, and 14 found an independent PBT effect. Pooled estimates of PBT effect on recurrence in randomised studies yielded an OR of 1.42 (95% CI, 1.20 to 1.67) against transfused patients. Stratified meta-analyses confirmed these findings also by site and stage of disease, regardless of timing, type, and in a dose-related fashion, although heterogeneity was detected. Data on surgical techniques was not available for further analysis. Authors' conclusions: This updated meta-analysis confirms the previous findings and supports the association of PBT on the recurrence of curable colorectal cancers. However, since heterogeneity was detected and the effect of surgical technique could not be assessed, a causal relationship cannot still be claimed. Carefully restricted indications for PBT seems necessary.