ABSTRACT
Background: Circulating tumor cells (CTCs) and microemboli (CTM) are attracting increasing attention in medical biology and clinical practice. However, the clinical relevance of CTCs in nasopharyngeal carcinoma (NPC) has not yet been ascertained, and no study has focused on the influence of Epstein-Barr virus (EBV) status on CTCs in NPC patients. These issues were therefore examined. Methods: Peripheral blood samples were prospectively obtained from 33 NPC patients before treatment. CTCs and CTM were captured using the Isolation by Size of Epithelial Tumor (ISET) method. Immunohistochemistry on CK5/6 (cytokeratin5/6) and P63, as well as in situ hybridization of EBERs (EBV-encoded RNAs) were used to validate the harvested tumor cells. Results: Out of 33 NPC patients, CTCs were detected in 22 cases (66.7%), and CTM were observed in 2 cases (6.1%). CTCs were presented in all stages of NPC patients but had no association with the TNM stages (all P > 0.05). The presence of CTCs appeared to correlate with EBV activation status. Among the total NPC patients, the EBV VCA-IgA levels in CTC-positive cases were higher than that in CTC-negative cases (negative vs. positive: 3.88 vs. 4.86, P = 0.016). A similar result was observed in the patients without distant metastasis (negative vs. positive: 3.76 vs. 4.95, P = 0.009). When the number of CTCs was considered, CTC counts were found to correlate with EBV VCA-IgA (R = 0.382, P = 0.041) and EBV DNA load (R = 0.396, P = 0.033) for all NPC patients as well as NPC patients without distant metastases. Conclusions: These findings strongly suggested detectable CTCs/CTM in all stages of NPC patients and support a positive correlation between CTCs and EBV activation in NPC patients.
Disclosure of potential conflicts of interest
No potential conflicts of interest were disclosed.
Funding
This study is supported by grants from the Science and Technology Plan Project of International Cooperation of Guangdong Province [grant number 2016A050502011 and 2014A050503033]; National Natural Science Foundation of China [grant number 81572665 and 81602426]; Science and Technology Program of Guangdong Province [grant number 2013B021800141]; Medical Science and Technology Research Fund Project of Guangdong Province [grant number A2015003]; and Natural Science Foundation of Guangdong Province [grant number 2016A030310198].