SummaryIntroductionPeri‐operative allogeneic red blood cell transfusion is hypothesised to increase the risk of cancer recurrence following cancer surgery. However, previous data supporting this association are limited by residual confounding. We conducted an umbrella review (i.e. a systematic review of systematic reviews) to synthesise and evaluate the evidence between red blood cell transfusion and cancer recurrence.MethodsWe searched online databases for systematic reviews of red blood cell transfusion and cancer‐related outcomes. The AMSTAR 2 tool was used for quality assessment. The adequacy of confounding adjustment was judged according to a consensus‐derived framework.ResultsWe included five relevant systematic views which included patient populations ranging from 2110 to 184,190. Two reviews reported cancer recurrence, and all reported an association with red blood cell transfusion. Three reviews reported positive associations between red blood cell transfusion and adverse outcomes including all‐cause mortality, recurrence‐free survival and cancer‐related mortality. According to AMSTAR 2, four reviews were rated as ‘critically low quality’ and one as ‘low quality’. There was variation in how systematic reviews assessed the risk of bias from confounding. Compared with our pre‐derived framework, we found a high likelihood of unmeasured confounding.DiscussionCurrently available evidence describes an association between peri‐operative red blood cell transfusion and cancer recurrence, but this is mostly of low to critically low quality, with minimal control for residual confounding. Further research, at low risk of bias, is required to provide definitive evidence and inform practice.

中文翻译：

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接受大型癌症手术的患者围手术期红细胞输注与癌症复发之间的关联：总括性综述*


摘要简介围手术期同种异体红细胞输注被认为会增加癌症手术后癌症复发的风险。然而，支持这种关联的先前数据受到残余混杂的限制。我们进行了一项总括性综述 （即系统综述的系统综述），以综合和评价红细胞输注与癌症复发之间的证据。方法我们检索了在线数据库，以查找红细胞输注和癌症相关结局的系统评价。使用 AMSTAR 2 工具进行质量评估。根据共识衍生的框架来判断混杂调整的充分性。结果我们纳入了 5 个相关的系统观点，包括 2110 至 184,190 患者群体。两项系统综述报告了癌症复发，所有系统综述都报告了与红细胞输注有关。三项系统综述报告了红细胞输注与不良结局之间的正相关，包括全因死亡率、无复发生存期和癌症相关死亡率。根据 AMSTAR 2 的数据，四条评论被评为“极低质量”，一条被评为“低质量”。系统评价评估混杂偏倚风险的方式存在差异。与我们预先推导的框架相比，我们发现未测量的混杂可能性很高。讨论目前可用的证据描述了围手术期红细胞输注与癌症复发之间的关联，但这大多是低质量到极低质量的，对残留混杂的控制最少。需要进一步的研究，以低偏倚风险提供明确的证据并为实践提供信息。