Intraoperative autologous blood recovery in prostate cancer surgery: in vivo validation using a tumour marker

Intraoperative autologous blood recovery during radical retro pubic prostatectomy has the potential of contamination with tumour cells. Its safety is proved by similar survival rates between allogeneic and autologous transfusion to oncology patients without standardization. Silencing of the gene encoding pi class of gluthatione-S transferase is a specific and sensitive molecular marker for prostate cancer, because it is present in more than 90% of prostate tumours. Using such tumour marker, we aimed to demonstrate that viable tumour cells could be eliminated using leucodepletion filters followed by irradiation.

Fifty patients with pi class of gluthatione-S transferase promoter hypermethylation in their primary prostate tumours were included in the analysis. Peripheral blood samples were collected during anaesthetic induction and recovered blood was collected throughout the surgery and then submitted to washing, leucoreduction and irradiation. Samples were analysed stepwise for the presence of promoter hypermethylation using real-time methylation-specific polymerase chain reaction.

Positive hypermethylation was found in recovered blood (two samples), recovered and washed blood (three samples), and recovered washed and filtered blood (two samples). After filtration and irradiation of the recovered blood, this marker could not be detected in any of the cases analysed, suggesting the absence of viable tumour cells.

Even though the risk of disseminating tumour cells in prostate cancer surgery by intraoperative autologous blood recovery is not yet fully established, no tumour-specific gene amplification was found after the association of blood filtration and irradiation, suggesting a significant reduction of such risk.