3.4. Dynamic detection of M/N ratio in NB plasma
The postoperative recurrence of NB patients is one of the key reasons for the high mortality of NB. Therefore, there is urgent need to develop early and dynamic monitoring methods for recurrence of NB. The clinical significance of MYCN in monitoring recurrence in NB patients was evaluated by dynamically monitoring the plasma M/N ratios of 9 patients with MNA cases after surgery. As shown in Fig 4, the plasma M/N ratio of 9 MNA NB patients dropped below 2.0 after surgical treatment, which is consistent with the M/N ratio of non-MNA amplified tumor patients. In addition, we found the M/N ratio of P2 and P9 was greater than 2.0 before 1-2 months recurrence. Therefore, NB plasma circulating cell-freeMYCN can be used as an early, non-invasive and dynamic monitoring indicator for relapse in NB patients.