Measuring circulating neuroblastoma cells by quantitative reverse transcriptase-polymerase chain reaction analysis.

Abstract

Histologic examination of bone marrow (BM) is an accepted clinical standard for the detection of metastatic neuroblastoma (NB). Circulating tumor cells in peripheral blood (PB) derive from depots other than BM, and its measurement may provide additional information in the management of patients with NB. One hundred twenty patients with Stage 4 NB were evaluated for tumor cell content in PB by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis of GD2 synthase mRNA with a sensitivity of 1 NB cell in 10(6) normal cells. These findings were correlated with qRT-PCR analysis of their simultaneously sampled BM aspirates and 5 standard modalities of disease detection (histology, computed tomography/magnetic resonance imaging, bone scan, metaiodobenzylguanidine scan, and urinary homovanillic acid/vanillylmandelic acid levels). Detection of GD2 synthase transcript was found in 62 patients: Eleven patients had positive (+) samples in their BM and PB (BM+PB+), 38 patients had BM+PB-negative (BM+PB-) specimens, and 13 patients had BM-PB+ samples. BM+PB+ paired samples had the highest transcript levels. When the extent of disease was scored (from 0 to 5) according to the number of positive disease detection modalities, the magnitude of the transcript level correlated with disease score. Ninety-one percent of patients with BM+PB+ samples had evidence of disease in >/= 3 modalities, whereas 97% of patients with BM-PB- samples and 100% of patients with BM-PB+ samples had low disease scores </= 2. Marker positivity in BM correlated with disease score. Patients who had positive marker in BM or PB had higher rates of relapse and death compared with patients who had negative marker. Kaplan-Meier analysis demonstrated a significantly greater risk of death for patients who had BM+PB+ specimens compared with patients who had BM-PB- samples (P = 0.03). BM monitoring should continue to be an integral part of disease follow-up for patients with Stage 4 NB. PB monitoring to complement tumor surveillance in the BM can be informative.