Evaluation of Minimal Residual Disease in Patients with Neuroblastoma

Neuroblastoma (NB) is a pediatric extracranial solid tumor that accounts for approximately 15% of all pediatric cancer deaths. More than 50% of patients with newly diagnosed NB are classified into a high-risk group with an approximately 50% long-term survival rate. Although most high-risk patients with NB achieve remission, more than half may have minimal residual disease (MRD) that eventually causes relapse. Looking towards an optimal outcome, the accurate evaluation of MRD in patients with NB (NB-MRD) is essential to monitor the treatment response and disease burden. Over the past decades, the quantification of NB-associated messenger RNA (NB-mRNA) by reverse transcriptase-polymerase chain reaction has become widely used to detect NB-MRD, owing to the lack of recurrent genomic aberrations in NB cells. To achieve a more accurate and sensitive detection, the current NB-MRD assays quantify a set of NB-mRNAs to detect NB cells in bone marrow, peripheral blood, and peripheral blood stem cell samples. Among a growing number of NB-MRD assays, several assays quantitating different but overlapping sets of NB-mRNAs are reported to have a significant prognostic value. However, the clinical significance of NB-MRD remains to be established. In this review, we summarize the recent progress in NB-MRD and evaluate its clinical value.