Circulating tumour cells (CTCs) have potential utility in various clinical applications for cancer management. The present study focused on evaluating the diagnostic role of CTCs in colorectal cancer (CRC). A total of 89 blood samples from 59 patients diagnosed with CRC and 30 healthy individuals were collected for CTC detection. The Cyttel method is an improved CTC detection strategy, which combines negative enrichment with immunofluorescence and fluorescence in situ hybridization. This method effectively detected a significant increase in total CTCs in patients with CRC (49/59) compared with those in healthy controls (3/30). A cut-off value of 2 CTCs/3.2 ml blood yielded a sensitivity of 83.05% and a specificity of 100%. Additionally, three traditional serum tumour markers, namely carcinoembryonic antigen (CEA), cancer antigen 19-9 (CA19-9) and CA72-4, were examined by immunoassays. The diagnostic sensitivity of CTCs was much higher than that of CEA, CA19-9 and CA72-4 alone or in combination, particularly in patients with early stage CRC. The combined sensitivity of CTCs and CEA reached 91.53%, which was only slightly lower than the sensitivity of all four markers combined (CTCs + CEA + CA19-9 + CA72-4). CTCs with aneuploidy of chromosome 7 or 8 were carefully distinguished, and the associations among different types of CTCs, clinicopathological characteristics and overall survival were statistically analysed. Total CTCs were revealed to be significantly associated with tumour differentiation and nerve invasion. CTCs were more likely to be detected in poorly differentiated CRC tumours than in well- and moderately-differentiated tumours (P=0.026). Furthermore, to the best of our knowledge, the present study was the first to report that CTCs with multiploidy of chromosome 7 were significantly associated with TNM stage. These CTCs exhibited a high chance of being identified in the peripheral blood of patients with late-stage CRC (stage III-IV; P=0.031). The present study suggests that the combination of CTCs and CEA may serve as an effective potential diagnostic and prognostic indicator in patients with CRC. Detection of CTCs with aneuploidy may have increased specificity in predicting highly malignant and invasive tumours in CRC management.
Keywords: Cyttel method; aneuploidy; circulating tumour cells; colorectal cancer; tumour markers.
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