Enrico Martin

256 Chapter 11 Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue sarcomas (STS) and comprise approximately 2% of all STS subtypes. 1 Neurofibromatosis type 1 (NF1) patients account for approximately 25-50% of MPNSTs; others occur sporadically or are radiation-induced. 2–5 Because of their origin in nervous tissue they may occur at any anatomical site. Treatment recommendations for localized disease follow general high- grade STS guidelines. 6 Surgical resection increases survival in MPNSTs and radiotherapy may be used to decrease local recurrences. 2–5 The role of chemotherapy in localized disease is being investigated, but remains controversial. 7,8 Despite aggressive treatment, the prognosis remains poor. 3 Oncological outcomes remain the focus in both STS and MPNST literature, and functional outcomes are infrequently described. The resection of any nerve in STS leads to significant decrease in function and quality of life. 9,10 MPNSTs have poor oncological outcomes and are particularly prone to major functional deficits after resection, yet little is known on the incidence and prevention of such morbidity. The resection of nerves, in contrast to only muscle tissue as in STS, may lead to both motor and sensory deficits. These deficits may be restored using functional reconstructions, yet such reconstructions are still rarely performed. 11–14 Reasons for this may be multifactorial, including the major focus on oncological outcomes, the unawareness of reconstructive possibilities, or the uncertainty of the effects of radiation and chemotherapy on the outcomes of reconstructions. Although amputation numbers have drastically fallen the last decades, major neurovascular involvement is still seen as a reason for amputation, commonly because of anticipated functional deficits. 15–17 The purpose of this study was to 1) investigate the incidence of postoperative motor and sensory deficits in MPNSTs; 2) identify patients at increased risk for such deficits; and 3) assess the use and outcomes of functional reconstructions. Methods Patient population MPNST patients diagnosed from 1988-2019 and receiving treatment in 10 cancer centers were included in this study. Follow-up was available until March 2020. Uncertain diagnoses were excluded based on pathological reports and available information during follow-up in patient files. The data request was approved by all ethical committees of participating centers. Covariates Patient-, tumor-, and treatment-specific covariates were retrospectively extracted from electronic patient files. Tumor sites were categorized into extremity, brachial plexus, head and neck (including intracranial sites), pelvic, core (including superficial and deep