Summary. There is emerging evidence of successful application of IOCS and leucocyte depletion filter in removing tumour cells from blood salvaged during various oncological surgeries. Research on the use of IOCS-LDF in MSTS is urgently needed. Introduction. Intra-operative cell salvage (IOCS) can reduce allogeneic blood transfusion requirements in non-tumour related spinal surgery. However, IOCS is deemed contraindicated in metastatic spine tumor surgery (MSTS) due to risk of tumour dissemination. Evidence is emerging from different surgical specialties describing the use of IOCS in cancer surgery. We wanted to investigate if IOCS is really contraindicated in MSTS. We hereby present a systematic literature review to answer the following questions: 1. Has IOCS ever been used in MSTS? 2. Is there any evidence to support the use of IOCS in other oncologic surgeries?. Methods. A systematic review of the English literature was conducted using computer searching of databases: Medline, Embase, the Cochrane Central Register of Controlled Trials for articles published between 1 January 1986 and 31 Dec 2012. Results. Question 1: A comprehensive literature search did not provide any publication describing the use of IOCS in MSTS. The application of IOCS in MSTS has never been described before. Question 2: Our systematic review shows that the use of IOCS has been extensively investigated in patients undergoing surgery for gynaecological, lung, urological, gastrointestinal, and hepatobiliary cancers. The literature review considered 281 abstracts from the initial search. After consideration by consensus, 30 articles were included in the final analysis. We included in our review -prospective, retrospective studies and in vitro studies. The selected articles were then classified according to the surgical specialty: gynaecological, lung, urological, gastrointestinal, and hepatobiliary cancers and type of studies: reinfusion studies, non-reinfusion studies and in vitro studies. 23 Reinfusion studies: Studies where salvaged blood was actually re-infused into patients and analyzed on the basis of clinical outcomes like survival, recurrence, metastasis rates, and transfusion requirements, etc. IOCS has been extensively investigated in several large cohort studies and large case series with considerable follow-up duration across urological, gynaecological, hepatobiliary and gastrointestinal cancers. Patients receiving salvaged blood have been shown to perform as well or better across a variety of clinical outcome measures as mentioned above. 2 in vitro studies and 5 non-reinfusion studies: Studies where salvaged blood was not re-infused into patients but was analyzed for the presence or viability of tumour cells in the processed blood. They consistently demonstrated the utility of LDF in either greatly reducing the number of tumour cells or even completely eradicating tumour cells from blood-tumour admixtures or salvaged blood. This provides the “proof-of-concept” that LDF is able and is effective in removing tumour cells from blood. Discussion/Conclusion. There is strong evidence that LDF can safely remove tumour cells from salvaged blood. IOCS in patients undergoing cancer surgery is not associated with any adverse clinical outcomes. The reluctance of spine surgeons to use IOCS in MSTS appears to be unsupported. There is ample evidence supporting the use of IOCS in oncological surgeries. Research is needed to evaluate the application of IOCS in MSTS

Summary. This is the first ever study to report the successful elimination of malignant cells from salvaged blood obtained during metastatic spine tumour surgery using a leucocyte depletion filter. Introduction. Catastrophic bleeding is a significant problem in metastatic spine tumour surgery (MSTS). However, intaoperative cell salvage (IOCS) has traditionally been contraindicated in tumour surgery because of the theoretical concern of promoting tumour dissemination by re-infusing tumour cells into the circulation. Although IOCS has been extensively investigated in patients undergoing surgery for gynaecological, lung, urological, gastrointestinal, and hepatobiliary cancers, to date, there is no prior report of the use of IOCS in MSTS. We conducted a prospective observational study to evaluate whether LDF can eliminate tumour cells from blood salvaged during MSTS. Patients & Methods. After Institutional Review Board (IRB) approval, 21 consecutive patients with metastatic spinal tumours from a known epithelial primary (defined as originating from breast, prostate, thyroid, renal, colorectal, lung, nasopharyngeal) who were scheduled for MSTS were recruited with informed consent. During surgery, a IOCS device (Dideco, Sorin Group, Italy) was used to collect shed blood from the operative field. Salvaged blood was then passed through a leucocyte depletion filter (RS1VAE, Pall Corporation, UK). 15-ml specimens of blood were taken from each of three consecutive stages: (i) operative field prior to cell saver processing (Stage A); (ii) transfusion bag post-cell saver processing (Stage B); (iii) filtered blood after passage through LDF (Stage C). Cell blocks were prepared by the pathology department using a standardised laboratory protocol. From each cell block, 1 haematoxylin and eosin (H&E) slide, and 3 slides each labelled with one of the following monoclonal mouse cytokeratin antibodies AE1/3, MNF 116 and CAM 5.2 were prepared. The cytokeratin antibodies are highly sensitive and specific markers to identify tumour cells of epithelial origin. These slides were read by one of two consultant pathologists who were provided full access to information on operative notes, but were blinded to the actual stages from which the slides were derived. Results. One case was excluded when the final diagnosis was revised to infection instead of metastatic spine tumour. Of the remaining cases, 7/21 tested positive for tumour cells in Stage A, 2 positive in Stage B. No specimen tested positive for tumour cells in Stage C. In 5 cases, posterior instrumentation without tumour manipulation was performed. Discussion/Conclusion. In this first-ever study of cell saver use in spine tumour surgery, we prove that leucocyte-depletion filters (LDF) can effectively eliminate tumour cells from blood salvaged during MSTS. It is now possible to conduct a clinical trial to evaluate IOCS-LDF use in MSTS. Our results are consistent with published results of similar studies performed on IOCS and LDF use outside the field of orthopaedic surgery. Spinal metastases originate from a myriad of primary cancers across various organ systems. If LDF can remove tumour cells from blood salvaged during surgery for spinal metastasis of different histological origin, then the finding can likely be extrapolated to several other fields of surgery where IOCS and LDF have not yet been attempted such as: neurosurgery, otolaryngology and general musculoskeletal oncology. Our results form a proof-of-concept for a paradigm shift in thinking regarding autotransfusion during spine tumour surgery