Background: MYCN amplification with subsequent MYCN protein overexpression is a powerful indicator of poor prognosis of neuroblastoma
patients. Little is known regarding the prognostic significance of the homologous MYC protein expression in neuroblastoma.
Methods: Immunostaining for MYCN and MYC protein was performed on 357 undifferentiated/poorly differentiated
neuroblastomas. Results were analysed with other prognostic markers.
Results: Sixty-seven (19%) tumours were MYCN( þ ), 38 (11%) were MYC( þ ), and one(0.3%) had both proteins( þ ). MYCN( þ )
tumours and MYC( þ ) tumours were more likely diagnosed in children418months with stage4-disease. MYCN( þ ) tumours were
associated with amplified MYCN, Unfavourable Histology (UH), and High-MKI (Mitosis–Karyorrhexis Index). MYC( þ ) tumours were
also frequently UH but not associated with MYCN amplification, and more likely to have low-/intermediate-MKI. Favourable
Histology patients without MYC/MYCN expressions exhibited the best survival (N ¼ 167, 89.7±5.5% 3-year EFS, 97.0±3.2% 3-year
OS), followed by UH patients without MYC/MYCN expressions (N ¼ 84, 63.1±13.6% 3-year EFS, 83.5±9.4% 3-year OS).
MYCN( þ )patients and MYC( þ )patients had similar and significantly low (Po0.0001) survivals (46.2±12.0% 3-year EFS,
63.2±12.1% 3-year OS and 43.4±23.1% 3-year EFS, 63.5±19.2% 3-year OS, respectively). Notably, the prognostic impact
imparted by MYC expression was independent from other markers.
Conclusions: In this series, B30% of neuroblastomas had augmented MYCN or MYC expression with dismal survivals. Prospective
study of MYC/MYCN protein expression signature as a new biomarker for high-risk neuroblastomas should be conducted
