MYCN gene plays an important role in neuroblastoma cell growth, apoptosis, differentiation, tumor infiltration, metastasis, and angiogenesis. MYCN gene amplification status in tumor tissue is one of the important clinical indicators of neuroblastoma risk. However, there are several problems in detecting the MYCN gene in tumor tissues, such as complex procedures in detection approaches, high detection costs, and difficulty in obtaining tumor tissues. Studies have shown that circulating-free MYCN gene amplification in neuroblastoma is consistent with that in tumor tissue. Circulating-free MYCN gene amplification has the advantages of high sensitivity, high specificity, simple operation, and non-invasiveness as an indicator for prognosis and recurrence of neuroblastoma. Therefore, the application and future development of circulating-free MYCN gene amplification status in the prognosis and recurrence monitoring of neuroblastoma was examined in this article.

The postoperative recurrence of neuroblastoma (NB) patients is an essential reason for the high mortality of NB due to the lack of early, non-invasive, and dynamic strategies for monitoring NB recurrence. Therefore, whether the plasma circulating cell-free MYCN gene as an indicator for monitoring of NB recurrence was systematically evaluated. The MYCN copy number and NAGK (reference gene) copy number ratio (M/N) in plasma and corresponding tumor tissues of NB patients was detected using an economical, sensitive and specific single-tube dual RT-PCR approach developed in this study. The plasma M/N ratio of the MYCN gene amplification (MNA) group (N = 25, median M/N ratio = 4.90) was significantly higher than that of the non-MNA group (N = 71, median M/N ratio = 1.22), P < 0.001. The M/N ratio in NB plasma (N = 60) was positively correlated with the M/N ratio in NB tumor tissue (N = 60), with a correlation coefficient of 0.9496. In particular, the results of dynamic monitoring of postoperative plasma M/N ratio of NB patients showed that an abnormal increase in M/N ratio could be detected 1-2 months before recurrence in NB patients. In summary, the single-tube double RT-PCR approache can be used to quantitatively detect MYCN copy number. The copy number of MYCN in the tissue and plasma of NB patients is consistent with each other. More importantly, the circulating cell-free MYCN gene of NB patients can be used as a monitoring indicator for early, non-invasive, and dynamic monitoring of NB recurrence.