Flow cytometry as the new ‘gold standard’ for detection of free tumour cells in abdominal lavage fluid in gastric cancer patients: A comparative study of molecular and conventional methods

Abstract

Aim:The ideal method for detection of free tumour cells in abdominal lavage fluid should be rapid, reliable and widely available. Flow cytometry potentially covers these properties, but there are only a few studies directly comparing flow cytometry for detecting gastric cancer cells to other methods. Therefore, we compared free tumour-cell detection in abdominal lavage fluids using cytology with immunocytochemistry, RT-qPCR and flow cytometry. Methods: Peritoneal lavage fluid samples were collected from 10 patients. Detection of free tumour cells was performed using cytological and immunocytochemical analysis, and using RT-qPCR and flow cytometry. Tumour cells were detected according to CEA and CK20 mRNA expression levels using RT-qPCR, and with the epithelial markers EpCAM/CD326 and CEA using flow cytometry. Results: The sensitivity and specificity of cytology were 40% and 100%, respectively, while the RT-qPCR had a sensitivity of 80% and specificity of 100%. Flow cytometry showed no false-negative results and only one false-positive result, giving a sensitivity and specificity of 100% and 80%, respectively. The RT-qPCR and flow cytometry could detect free tumour cells in each of the three false-negative cases with cytology. In the samples with detected tumour cells, tumour cell clusters were observed with imaging flow cytometry, providing additional morphological confirmation. Conclusion: The combination of quantitative and qualitative data from flow cytometry and the images of tumour cells in borderline cases provide a rapid, reliable and reproducible method for detection of free tumour cells in abdominal lavage fluid, which is necessary for intraoperative selection of patients for intraperitoneal chemotherapy.

Development of the PERI-Gastric (PEritoneal Recurrence Index) and PERI-Gram (Peritoneal Recurrence Index NomoGRAM) for predicting the risk of metachronous peritoneal carcinomatosis after gastrectomy with curative intent for gastric cancer

“…Due to these current limitations, patients with positive cytology are usually included in trials on prophylactic HIPEC [41,42]. Due to the relevance of this topic, a widespread use of diagnostic laparoscopy and the effort to introduce fast and reliable techniques for cytology in every gastric cancer center should be valued to improve the intraoperative estimation of the risk of peritoneal diffusion (due to pre-existing peritoneal free cancer cells or contamination occurring during surgery) [54,55]. This is the largest multicentric Western study that developed a prognostic model to assess the risk of peritoneal recurrence after gastrectomy with curative intent.…”