应用FR靶向PCR法检测CTC在肺癌诊断中的临床价值:初步研究

Diagnostic Value of Folate Receptor-positive Circulating Tumor Cell in Lung Cancer: A Pilot Study

背景与目的评价一种通过叶酸受体(folate receptor,FR)检测循环肿瘤细胞(circulating tumor cell,CTC)的方法用于肺癌临床诊断的实用性和可行性及进一步探究CTC在肺癌术后复发的预测价值。方法通过免疫磁珠负向富集方法从3 m L外周血中捕获循环肿瘤细胞,再用肿瘤特异性叶酸配体-寡核苷酸偶和物标记捕获的循环肿瘤细胞,洗去没有结合的偶和物后,洗脱下特异性结合的偶合物的寡核苷酸用于定量PCR扩增分析。结果 97例肺癌患者的CTC水平高于肺部良性疾病患者(P<0.001)。本检测方法以8.7 Folate Units/3 m L为cutoff值,结果显示靶向PCR法对肺癌的检测灵敏度为82.5%,特异性为72.2%,特别是在I期肺癌灵敏度达到86.8%。与其他肿瘤标志物(NSE、CEA、CYFRA21-1)比较,CTC对肺癌及I期肺癌具有较高的诊断准确性(0.859;95%CI:0.779-0.939)和(0.912;95%CI:0.829-0.994)。5例肺癌患者术后2周内CTC水平高于cutoff值。结论叶酸受体阳性循环肿瘤细胞可以应用于肺癌的临床诊断,即使是对早期非小细胞肺癌(non-small cell lung cancer,NSCLC)的诊断。

Background and objective The aim of this study is to determine the efficacy and feasibility of a novel folate receptor （FR）-based circulating tumor cell （CTC） detection method in the diagnosis of lung cancer. CTCs were col- lected from 3 mL of blood based on negative enrichment by immunomagnetic beads and then labeled by a conjugate of a tumor-speciflc ligand folate and an oligonucleotide. Methods After washing off redundant conjugates, the bound conjugates were removed and analyzed by quantitative polymerase chain reaction. Results ＂l-he CTC levels of 97 patients with lung cancer were significantly higher than that of the controls （18 patients with benign lung diseases; P〈0.001）. With a threshold of 8.7 Folate units, the method showed a sensitivity of 82.5% and a specificity of 72.2% in the diagnosis of lung cancer, especially a sensitivity of 86.8% in stage I disease. Compared with the existing clinical biomarkers such as neuron-specific enolase （NSE）, carcinoembryonic antigen （CEA）, and CYFK421-1, the method showed the highest diagnostic efficiency in lung cancer （area under the curve, 0.859; 95%CI： 0.779-0.939） and stage I lung cancer （area under the curve, 0.912; 95%CI： 0.829-0.994）. For future work, the CTC levels of 5 lung cancer patients higher than 8.7 Folate units/3 mL in their postoperation. Conclusion FR-positive CTCs were feasible diagnostic biomarkers in patients with lung cancer, as well as in early-stage tumors.