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Neuro Oncol. 2015 Jan;17(1):63-9. doi: 10.1093/neuonc/nou140. Epub 2014 Jul 19.

Methylated RASSF1A in malignant peripheral nerve sheath tumors identifies neurofibromatosis type 1 patients with inferior prognosis.

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Department of Cancer Prevention, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, Oslo, Norway (S.A.D., G.E.L., M.K., M.H., R.A.L.); Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Oslo, Norway (S.A.D., G.E.L., M.K., M.H., R.A.L.); Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway (M.H., S.S.); Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway (S.A.D., G.E.L., R.A.L.); Department of Pathology (B.B), Division of Diagnostics and Intervention and Department of Oncology, Division of Cancer, Surgery and Transplantation, Oslo University Hospital-The Norwegian Radium Hospital, Oslo, Norway (K.S.H., S.S.); Department of Medical Genetics, University Hospital of Groningen, The Netherlands (E.v.d.B.); Department of Clinical Genetics, Skåne University Hospital, Lund, Sweden (F.M.); Laboratory of Oncologic Research of the Istituto Ortopedico Rizzoli, Bologna, Italy (P.P.).



Malignant peripheral nerve sheath tumor (MPNST) is a rare and highly aggressive disease with no evidence of effect from adjuvant therapy. It is further associated with the hereditary syndrome neurofibromatosis type 1 (NF1). Silencing of the tumor suppressor gene RASSF1A through DNA promoter hypermethylation is known to be involved in cancer development, but its impact in MPNSTs remains unsettled.


The RASSF1A promoter was analyzed by methylation-specific PCR in 113 specimens, including 44 NF1-associated MPNSTs, 47 sporadic MPNSTs, 21 benign neurofibromas, and 1 nonneoplastic nerve sheath control.


RASSF1A methylation was found only in the malignant samples (60%) and identified a subgroup among patients with NF1-associated MPNST with a poor prognosis. These patients had a mean 5-year disease-specific survival of 27.3 months (95% CI: 17.2-37.4) versus 47.4 months (95% CI: 37.5-57.2) for NF1 patients with unmethylated promoters, P = 0.014. In multivariate Cox regression analysis, methylated RASSF1A remained an adverse prognostic factor independent of clinical risk factors, P = .013 (hazard ratio: 5.2; 95% CI: 1.4-19.4).


A considerable number of MPNST samples display hypermethylation of the RASSF1A gene promoter, and for these tumors, this is the first molecular marker that if validated can characterize a subgroup of patients with inferior prognosis, restricted to individuals with NF1.


MPNST; NF1; RASSF1A; methylation; survival

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