Early detection is the hallmark of successful cancer treatment. Evidence is accumulating that primary cancers begin shedding neoplastic cells in the circulation at an early stage. To date, a high-sensitivity and high-throughput method for the detection of circulating tumor cells (CTCs) is deficient. In this study, we have developed a high-sensitivity colorimetric membrane-array method to detect CTCs in the peripheral blood of colorectal cancer (CRC) patients as a potential diagnostic tool. Previously, we identified a set of 18 oligonucleotide clones, significantly overexpressed in CRC, which were synthesized and applied to a nylon membrane. Digoxigenin (DIG)-labeled cDNA were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) from the peripheral blood of 88 Taiwanese CRC patients and 50 healthy subjects, and were then hybridized to the membrane-array. Hybridization signals were detected by color development. Meanwhile, blood samples were analyzed by real-time quantitative PCR (Q-PCR). Subsequently, both methods were compared regarding their correlation, sensitivity and specificity in the detection of CTCs by statistics. The results of membrane-arrays were demonstrated to be closely related to that of Q-PCR (P<0.001). The sensitivity and specificity of membrane-arrays for the detection of CTCs were 94.3% (95% CI, 86.4-102.2%) and 94% (95% CI, 85.9-102.1%), respectively. Moreover, the accuracy of membrane-arrays is higher than that of any one gene by Q-PCR. The detection rate of membrane-arrays was significantly associated with the depth of tumor invasion (P=0.002), the presence of lymph node metastasis (P=0.016), and TNM stage (P=0.005). The preliminary results indicated that the accuracy of membrane-arrays was sufficient to distinguish Taiwanese CRC patients from normal individuals with the advantages of time-saving, cost-effectiveness and high-throughput. Thus, the constructed colorimetric membrane-array could be a promising approach for the future detection of CTCs.

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