Prediction of MYCN amplification in neuroblastoma using serum DNA and real-time quantitative polymerase chain reaction.
OBJECTIVE
MYCN amplification (MNA) indicates a poor prognosis in neuroblastoma (NB) and is routinely assayed for therapy stratification. We aimed to develop a diagnostic tool to predict MYCN status using serum DNA, which, in cancer patients, predominantly originates from tumor-released DNA.


METHODS
Using DNA-based real-time quantitative polymerase chain reaction, we simultaneously quantified MYCN (2p24) and a reference gene, NAGK (2p12), and evaluated MYCN copy number as an MYCN/NAGK (M/N) ratio in 87 NB patients whose MYCN status had been determined by Southern blotting. Of these patients, 17 had MYCN-amplified NB, and 70 had nonamplified NB.


RESULTS
The serum M/N ratio in the MNA group (median, 199.32; range, 17.1 to 901.6; 99% CI, 107.0 to 528.7) was significantly (P < .001) higher than the ratio in the non-MNA group (median, 0.87; range, 0.25 to 4.6; 99% CI, 0.82 to 1.26; Mann-Whitney U test). The sensitivity and specificity of the serum M/N ratio as a diagnostic test were both 100% when the serum M/N ratio cutoff was set at 10.0. Among six MNA patients whose clinical courses were followed, the serum ratios decreased to the normal range in the patients in remission (n = 3), whereas the ratios increased to high levels in the patients who relapsed (n = 2) or failed to achieve remission (n = 1).


CONCLUSIONS
Measurement of the serum M/N ratio seems to be a promising method for accurately assessing MYCN status in NB, although a larger set of patients needs to be examined to confirm this result.
Gotoh
Takahiro
T
Department of Pediatrics, Kyoto Prefectural University of Medicine, Graduate School of Medical Science, Kamigyo-ku, Kyoto 602-8566, Japan. takahiro_email@yahoo.co.jp
Hosoi
Hajime
H
Iehara
Tomoko
T
Kuwahara
Yasumichi
Y
Osone
Shinya
S
Tsuchiya
Kunihiko
K
Ohira
Miki
M
Nakagawara
Akira
A
Kuroda
Hiroshi
H
Sugimoto
Tohru
T
D000293:Adolescent; D015139:Blotting, Southern; D002648:Child; D002675:Child, Preschool; D004273:DNA, Neoplasm / Q000032:analysis*; D003937:Diagnosis, Differential; D005260:Female; D005784:Gene Amplification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000175:diagnosis / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011379:Prognosis
D004273:DNA, Neoplasm; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins