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 due to the hypothetical concern of reinfusion of malignant cells. We evaluated the feasibility of IOCS in combination with leucocyte depletion filter (LDF) in metastatic spine tumour surgery (MSTS).

Methods: Patients with known primary epithelial tumour, operated for metastatic spinal disease, were recruited. Blood samples were collected at five different stages during surgery: 2 stages from patient vein during induction and at the time of maximum tumour manipulation, 3 stages from the operative blood prior to IOCS processing, after IOCS processing, and after IOCS-LDF processing. Of the samples taken at each stage, 5 ml were analyzed for tumour cells using flow cytometry.

Results: Of 12 patients recruited, only 11 could be finally analyzed. Flow cytometry analysis of their samples showed that 8 of 11 patients had tumour cells in the unfiltered salvaged blood. In filtered salvaged blood, the tumour cell count was zero in the majority of samples (8/11 patients), whereas three patients' samples had a few tumour cells. The mean difference between the tumour cell quantity in the samples from the patient vein and filtered salvaged blood was significant.

Conclusions: IOCS-LDF was shown to be effective in removing tumour cells from the blood salvaged during MSTS. If there were any tumour cells found, the quantity was significantly less than that in the patient's circulation. The results of this study reiterates the conclusions of our previous published work where we showed that IOCS-LDF treated blood in MSTS is safe for transfusion.