Authors' reply: Meta-analysis of defunctioning stomas in low anterior resection for rectal cancer (Br J Surg2009; 96: 462-472)

Sir The authors’ hypothesis that renal transplants survive better in patients following blood transfusion is presumed to be due to immunomodulation, but it may equally be explained by the transfusion promoting new vessel growth1,2. Indeed, vascular endothelial growth factor (VEGF) accumulating during blood storage may also explain why so many studies have shown reduced transfusionrelated cancer survival. Non-leucodepleted blood may contain more VEGF as white cells store VEGF, but as the authors concede there are still significant numbers of white cells present in leucodepleted blood. Thus the contradictory results of over 150 studies examining blood transfusion and cancer recurrence may be explained not only by the type of blood (leucodepleted or not) but also the age of the stored blood. As this study did not mention the concept of transfusion-induced angiogenesis, I wonder if this may be considered by the authors to explain their results. If possible they may be able to review their data to report on the storage age of the blood transfused (between 1 and 35 days old). Recording these data may make the next 150 such studies unnecessary. G. Nash Poole Hospital, Poole, UK DOI: 10.1002/bjs.6882