Comparison of three distinct methods for the detection of circulating tumor cells in colorectal cancer patients

Abstract

Abstract. the detection of circulating tumor cells (ctcs) has considerable utility in the clinical management of patients with solid cancers. However, the phenotypic heterogeneity of ctcs and their low numbers in the bloodstream of patients means that no standardized detection method currently exists for these cells. this, together with differences in pre-analytical sample processing, has led to the collection and accumulation of inconsistent data among independent studies. Here, we compare the ability of three methods to detect ctcs in the blood of colorectal cancer patients. specifically, different aliquots of the same blood sample were screened for the presence of ctcs by a multimarker rt-pcr assay, the standardized cellsearch assay and dHplc-based gene mutation analysis. In the population tested, none of the blood samples analysed appeared to be positive by all three methods. of the samples, 75% were positive for the presence of ctcs by the rt-pcr method. only 20% were positive by the cellsearch assay, while 14.3% of samples displayed gene mutations consistent with the presence of ctcs when the dHplc method was applied. the samples which were positive for ctcs by the cellsearch assay did not overlap with those that were positive by dHplc. Interestingly, however, all of these samples were positive when assessed by rt-pcr. conversely, of the samples that resulted negative by rt-pcr analysis, none appeared to be positive by either of the other methods. these data, therefore, indicate that of the three methods tested, the multimarker rt-pcr assay provides maximal probability of ctc detection. Here, we present the preliminary results of an ongoing clinical study. Future follow-up involving detection of ctcs in the blood of colorectal cancer patients using these three distinct methods will allow us to verify whether either a single method, or a combination of different assays, is necessary to uncover further prognostic significance of circulating tumor cells.

Comparison of three molecular assays for the detection and molecular characterization of circulating tumor cells in breast cancer

“…However, another study has revealed that the AdnaTest BreastCancer™ has equivalent sensitivity to that of the CellSearch in detecting two or more CTC [40]. Moreover, recent studies, especially in early breast cancer, have also shown a superior sensitivity of molecular assays with respect to the CellSearch [11,21,25,28]. In most of these comparison studies, discrepancies found between the different assays were partly explained by the fact that these molecular assays were using different capture technologies for CTC isolation and very different detection systems.…”

Clinical and biological significance of circulating tumor cells, circulating tumor DNA, and exosomes as biomarkers in colorectal cancer

“…Epithelial cell adhesion molecule (EpCAM) expression was approximately 10-fold lower on CTCs compared to on primary and metastatic tissues, suggesting that it is dependent on the local microenvironment and is down-regulated on CTCs [ 31 ]. This may be the reason why CTCs were undetected by the CellSearch™ System in a significant proportion of patients with CRC [ 32 ]. Although the CellSearch™ is the only FDA-approved technology applied for CTC enrichment, it cannot capture non-epithelial CTCs, such as the CTCs that have undergone EMT, resulting in a missed detection.…”

Imaging Circulating Tumor Cells in Freely Moving Awake Small Animals Using a Miniaturized Intravital Microscope

“…[5], [6] However, heterogeneous results have been obtained when comparing CTCs enumerated in the same patient blood samples using different CTC detection technologies. [7]–[11] …”