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

Results. 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 ¼ 0.014. In multivariate Cox regression analysis, methylated RASSF1A remained an adverse prognostic factor independent of clinical risk factors, P ¼ .013 (hazard ratio: 5.2; 95% CI: 1.4– 19.4). Conclusion. 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.