By Naresh Kumar
Metastatic spine disease can be regarded as new epidemic, which can present in 30% to 90% of patients with cancer. Surgical management of metastatic spine disease is usually associated with significant blood loss. Currently, allogeneic blood is the mainstay for replenishing blood loss and as a result, there is an undue strain on limited blood bank resources. Furthermore, despite improvement in the screening for the safety of its transfusion, deleterious effects such as transmission of infections, immunosuppression and transfusion reaction are still detected in the transfused patients.
Intraoperative cell salvage has been routinely employed in elective surgery in several disciplines as a good alternative to allogeneic blood. Its use is controversial in cancer surgery because of a theoretical concern of contaminating the blood salvaged with malignant cells during surgery (and hence promoting tumour dissemination). But, there is emerging evidence from several studies that intraoperative cell salvage can reduce the allogeneic transfusion requirements with no significant side effects. There is also increasing evidence that the combination of leucocyte depletion filters and intraoperative cell salvage can aid the complete removal of tumour cells from salvaged blood.
We recently performed a systematic review of the literature to explore whether intraoperative cell salvage has been applied in metastatic spine tumour surgery, and also whether it has been used other cancer surgeries. The literature search did not provide any publication on the use of intraoperative cell salvage in metastatic spine tumour surgery, but we did identify that intraoperative cell salvage has been extensively investigated in various oncological surgeries (namely hepatobiliary, gastrointestinal, and gynaecological, urological) with evidence presented in 281 publications. After rigorous and predefined selection criteria, we had 30 publications available for review. These studies were categorised into three types: 23 reinfusion studies where the salvaged blood was re-infused to the patients during surgery and followed-up over a period of time to assess outcome measures (such as survival, tumour recurrence rate and distant metastasis); five non-re-infusion studies in which the salvaged blood was not re-infused but analysed for the presence/absence of tumour cells in the salvaged blood; and two in vitro studies in which the salvaged blood is spiked with tumour cells lines and investigated the efficacy of leucocyte depletion filters in removing tumour cells. The non-re-infusion and in vitro studies showed that intraoperative cell salvage-leucocyte depletion filters could effectively remove the tumour cells from the salvaged blood or blood-tumour admixture; “proof-of-concept” with this approach has been shown. Clinical re-infusion studies provided more robust evidence that patients who received salvaged blood during cancer surgeries (ie. hepatobiliary, gastrointestinal, gynaecological, urological and lung cancers) had similar or even superior results as compared with those who received no blood or allogeneic blood transfusion. Based on this evidence, the view that intraoperative cell salvage is not suitable for use in patients with metastatic spine disease may not be valid.
We have conducted a prospective study to look at the use of salvaged and filtered blood in 40 consecutive patients who underwent metastatic spine tumour surgery at our institution. All of these patients had metastatic spine disease, from epithelial primary tumours, that required surgery. Using the cell block technique, we found that filtered salvaged blood did not contain any viable tumour cells, making it safe for reinfusion. We still recommend further prospective cohort studies to further evaluate the clinical application of intraoperative cell salvage-leucocyte depletion filters in patients undergoing metastatic spine tumour surgery.
Naresh Kumar, associate professor Orthopaedics, senior consultant Orthopaedics, National University Health System, National University of Singapore, Singapore