DETECTION OF MINIMAL TUMOR CELLS FOR THE DIAGNOSIS AND TREATMENT MONITORING OF CHILDREN WITH NEUROBLASTOMA

Abstract

Diagnosis, treatment and designing an adequate strategy of neuroblastoma (NB) therapy in children is still a complicated tasks for pediatric oncology and hematology. One of the key aspects of NB control is detection and monitoring of minimal residual disease.The authors make a concise review of the up-to-date methods, such as immunocytochemistry, fluorescent in situ hybridization (FISH), flow cytometry, the methods of qualitative and quantitative polymerase chain reaction (PCR) to estimate mRNA (RT-PCR and QRT-PCR), which are currently used for minimal residual disease detection in patients with NB. Disialoganglioside GD2, a specific NB marker, is traditionally determined by immunocytochemistry with fluorochromes that enhance its specificity, and by flow cytometry, as well. At present, FISH test is a gold standard for evaluation of the MYCN gen status in NB. A widely used multicolor flow cytometry method allows achieving high specificity of the analysis for NB diagnosis. RT-PCR may search for various targets to reveal NB cells, however, at the moment the only accepted immune target is tyrosine hydroxylase mRNA. Moreover, the studies established that quantitative QRT-PCR has more advantages than traditional qualitative RT-PCR, since this method allows a more accurate and quantitative detection of one or several mRNAs in clinical samples. The review discusses advantages and disadvantages of the main methods currently used for minimal residual disease evaluation of NB cells, such as RT-PCR, flow cytometry, FISH, etc. Comparative studies included multicolor flow cytometry with various combinations of CD9/CD81/CD56/CD45/GD2 monoclonal antibodies, conventional RT-PCR and quantitative QRT-PCR to reveal circulating/disseminated NB cells in the clinical samples of cancer patients and healthy volunteers.The authors analyze the results of various studies that compared accuracy and sensitivity of diagnostic methods such as RT-PCR, flow cytometry, FISH and some others. Despite the advantages of each method, the authors emphasize that multicolor flow cytometry is the optimal approach for the rapid and reliable detection of minimal residual disease and micrometastases of NB.