Malignant peripheral nerve sheath tumors (MPNST): the Mayo Clinic experience.

Background: Malignant peripheral nerve sheath tumors (MPNST) are a rare form of soft tissue sarcoma with few studies reporting on patient outcomes and prognostic variables.

Methods: A retrospective review of 175 patients diagnosed with MPNST from 1985 to 2010 was performed. Patient, tumor, and treatment characteristics were evaluated to identify prognostic variables.

Results: The median age of our study population was 44 years, and 51% were female. Median tumor size was 6 cm, and 61% of patients had high-grade tumors. Tumors were most commonly located on the extremities (45%), then trunk (34%) and head/neck (19%). The majority of patients underwent surgical resection (95%) and adjuvant treatment with chemotherapy (6%), radiation (42%) or both (22%). Margin status was R0 in 69%, R1 in 2%, R2 in 9%, and unknown in 20%. The local recurrence rate was 22%, and 5- and 10-year disease-specific survival (DSS) were 60% and 45%, respectively. On univariate analysis, no predictors for local recurrence were identified. Tumor size ≥ 5 cm, high tumor grade, tumor location, presence of neurofibromatosis type 1, local recurrence, and adjuvant chemotherapy were all associated with DSS. On multivariate analysis, size ≥ 5 cm [hazard ratio (HR)= 6.1, 95% confidence interval (CI) 1.5-25.0], local recurrence (HR = 4.4, 95% CI 1.7-11.4), high tumor grade (HR = 3.8, 95% CI 1.1-13.2), and truncal location (HR = 3.7, 95% CI 1.1-12.7) were poor prognostic indicators for DSS.

Conclusions: High tumor grade and tumor size ≥ 5 cm predict adverse DSS for MPNST. In the context of a multidisciplinary treatment regimen, local recurrence and survival outcomes at 5 and 10 years were better than previously reported for MPNST.