Flow Cytometric Evaluation of the Safety of Intraoperative Salvaged Blood Filtered with Leucocyte Depletion Filter in Spine Tumour Surgery

Background Intraoperative cell salvage (IOCS) has not been widely adopted in oncological surgery because of hypothetical concern of reinfusion of malignant cells. We conducted the study to evaluate the feasibility of IOCS in combination with leukocyte depletion filter (LDF) in metastatic spine tumor surgery (MSTS) using quantitative flow cytometry tumor detection technique. Methods Patients with known primary epithelial tumor, operated for metastatic spinal disease, were recruited. Blood samples were collected at five different stages during surgery: two stages from patient vein during induction and at the time of maximum tumor manipulation, three stages from the operative blood before IOCS processing, after IOCS processing, and after IOCS–LDF processing. Of the samples taken at each stage, 5 mL were analyzed for tumor cells using flow cytometry. Results Of the 12 patients recruited, only 11 could be finally analyzed. Flow cytometry analysis of their samples showed that 8 of 11 patients had tumor cells in the unfiltered salvaged blood. In filtered salvaged blood, the tumor cell count was zero in the majority of samples (8/11 patients) whereas three patients' samples had a few tumor cells. The difference between the mean tumor cell quantity in the samples taken from stages A and E was significant ( p = 0.04). Similarly, the difference between the mean quantities of tumor cells in the samples in stages B and E was significant ( p = 0.01). However, there were no significant differences between the mean quantities of tumor cells when comparing the samples from either stages A and B, stages D and E, or stages C and E. Conclusion IOCS–LDF was shown to be effective in removing tumor cells from blood salvaged during MSTS. If there were any tumor cells found, the quantity was significantly less than that in patient's circulation. The results of this study supported that fact that IOCS–LDF treated blood in MSTS is safe for transfusion.