Background: We evaluated the diagnostic value of plasma Macrophage inhibitory cytokine-1 (MIC-1) in distinguishing patients with nasopharyngeal carcinoma (NPC) and explored its complementary role with widely used Epstein-Barr virus (EBV) related markers, EBV capsid antigen-specific IgA (VCA-IgA) and EBV copy number.
Methods: ELISA was used to analyze the plasma MIC-1 levels in 190 NPC patients, 72 VCA-IgA-positive healthy donors (VP), and 219 normal subjects with negative VCA-IgA (VN). 10 pairs of plasma samples before and after radiotherapy were also included.
Results: The plasma MIC-1 levels were significantly higher in NPC patients (Median: 678.39 ng/mL) than those in VN and VP (310.29 and 294.59, p < 0.001). Receiver operating characteristic (ROC) curves of the MIC-1 concentrations revealed that the area under the ROC curve (AUC) was 0.790 (95% confidence interval [CI]: 0.748-0.832), with a sensitivity of 63.7%, and a specificity of 85.9% respectively, for distinguishing NPC patients from the healthy donors. Similarly, between NPC and VP, ROC was 0.796 (0.738-0.853) with sensitivity of 63.7%, and specificity of 88.9%. In addition, between NPC and VN, ROC was 0.788(0.744-0.832) with sensitivity of 63.7%, and specificity of 84.9%. Further, we found that MIC-1 could complement VCA-IgA and EBV DNA markers, with a negative rate of 88.9% in VCA-IgA-positive healthy controls, and a positive rate of 59.0% in EBV DNA negative NPC patients, respectively. Also, the MIC-1 plasma concentration dropped significantly after radiotherapy (p = 0.027).
Conclusions: MIC-1 can complement VCA-IgA titers and EBV DNA copy number tests in NPC detection, improve identification of EBV DNA-negative NPC patients, and distinguish NPC from VCA -IgA positive healthy controls.
Keywords: EBV DNA; MIC-1; VCA-IgA; nasopharyngeal carcinoma; radiotherapy.