The detection of circulating tumour cells in oesophageal adenocarcinoma

Abstract

The incidence of oesophageal adenocarcinoma is rising. Overall survival rates remain poor. Traditional methods of staging oesophageal adenocarcinoma fail to identify patients at high risk of early disease recurrence after surgical treatment with curative intent. Circulating tumour cells have been reported to offer prognostic information in patients with certain tumour types including breast, prostate and colorectal. The majority of studies have focused on circulating tumour cell enumeration in patients with metastatic disease. Little is known about the role of circulating tumour cells in oesophageal adenocarcinoma or of the importance of circulating tumour cells in patients without metastatic disease. Cultured oesophageal adenocarcinoma cell lines were used to develop and validate a novel method for detection of tumour cells in whole blood. The method used positive depletion of normal blood cell populations before imaging the cells with an Imagestreamx image flow cytometer. A panel of fluorescently-conjugated antibodies against EpCAM, cytokeratins, survivin, CD45 and DAPI were used to discriminate the tumour cells. A consistent recovery of 48% was achieved across a range of concentrations of cultured oesophageal adenocarcinoma cells added to whole blood. Blood samples from 25 patients undergoing staging for oesophageal adenocarcinoma without known distant metastatic disease were studied. Circulating tumour cells were identified in 5 patients, range 2 – 85 per 5 ml whole blood. Circulating tumour-associated macrophages were identified in a single patient. No difference in overall survival was demonstrated between those patients with circulating tumour cells compared to those without. The developed method produces high quality images allowing for the detection and characterisation of circulating tumour cells. Heterogeneity within the circulating tumour cell population was observed. Circulating tumour cells may be identified in a significant number of patients with oesophageal adenocarcinoma without radiological evidence of distant metastatic disease.