Outcomes following definitive treatment of malignant peripheral nerve sheath tumor are significantly worse for patients with neurofibromatosis type 1: A Canadian Sarcoma Research and Clinical Collaboration study.

BACKGROUND: Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas with a 5-year survival rate of approximately 50%, secondary to their metastatic potential and resistance to therapy. MPNSTs can arise sporadically, as a late toxicity from therapeutic radiotherapy, or in patients with neurofibromatosis type 1 (NF1). Prior studies have demonstrated conflicting results regarding the prognosis of NF1 associated MPNST compared to non-NF1 associated MPNST (NF0). The authors hypothesized that NF1-associated MPNSTs metastasize at a higher rate and are therefore associated with worse clinical outcomes.

METHODS: The authors collected data from 166 MPNST patients included in the Canadian Sarcoma Research and Clinical Collaboration (CanSaRCC) database. Of these, 54 had NF1. Patient demographics, overall survival (OS), cumulative incidence of progression or relapse (CIPR), and cumulative incidence of disease metastasis (CIDM) were assessed.

RESULTS: Patients with NF1 were younger (p < .001) and had larger tumors at MPNST diagnosis (p < .001). Two-year OS was lower, and CIPR and CIDM were higher in NF1-associated compared to NF0 MPNST. NF1 status, stage at diagnosis, tumor size, and positive surgical margins were adversely correlated to OS. Tumor location was an adverse prognostic factor for CIPR, and tumor size was the only adverse predictor for the CIDM in patients who underwent surgery.

CONCLUSION: In summary, this study suggests that patients with NF1-associated MPNSTs experience worse outcomes. NF1 associated MPNSTs were larger and arose in locations less amenable to negative (R0) resections. Among resectable tumors, CIDM, the primary driver of survival in patients initially diagnosed with localized disease, was correlated to tumor size but not NF1 status.