Intraoperative cell salvage in metastatic spine tumour surgery reduces potential for reinfusion of viable cancer cells

This study aimed at evaluating our hypothesis that tumour cells, which pass through the intraoperative cell salvage (IOCS) machine, lose viability due to possible injury to the cell membrane during centrifugation and filtration, enabling safe reinfusion even without filtration. Thirteen patients who underwent metastatic spine tumour surgery (MSTS) at our institution were recruited. Blood samples (5 ml each) were collected at five different stages during surgery, namely, stage A and B: from patients' vein during induction and at the time of maximum tumour manipulation; stage C, D and E: from the operative blood prior to IOCS processing, after IOCS processing and after IOCS-LDF (leucocyte depletion filter) processing, respectively. The samples were then analysed for viability of tumour cells using microwell-based culture. The median age of the patients was 65 years (range 37-77 years). The most common primary tumour was lung, followed by breast, hepatocellular and renal cell carcinoma. The median blood loss was 680 ml (range 300-1500 ml). Analysis of cultured blood samples showed that CTC-containing clusters were developed from some samples before IOCS-LDF processing (stage A: three patients, stage B: three patients and stage C: one patient). None of the samples from stages D and E generated clusters after culture, suggesting the absence of viable cancer cells after IOCS processing. The salvaged blood may contain some tumour cells after processing with IOCS machine, but these cells are damaged and hence unable to replicate and unlikely to metastasise. The results of this study support the hypothesis that salvaged blood in MSTS is safe for transfusion.