Malignant peripheral nerve sheath tumors of the spine: results of surgical management from a multicenter study

Abstract

OBJECTIVE Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft-tissue sarcomas. Resection is the mainstay of treatment and the most important prognostic factor. However, complete resection of spinal MPNSTs with tumor-free margins is challenging due to the likelihood of residual tumor cells. The objective of this study was to describe whether the type of Enneking resection in the management of spinal MPNSTs had an effect on local recurrence and survival. METHODS The AOSpine Knowledge Forum Tumor developed a multicenter database that includes demographic, diagnostic, therapeutic, local recurrence, and survival data on patients with primary spinal column tumors. Patients who had undergone surgery for a primary spinal MPNST were included and were analyzed in 2 groups: 1) those undergoing Enneking appropriate (EA) resections and 2) those undergoing Enneking inappropriate (EI) resections. EA surgery was performed if there was histopathological evidence of an intact tumor pseudocapsule and at least a marginal resection on a vital structure. EI surgery was performed if there was an intentional or inadvertent transgression of the margin. RESULTS Between 1993 and 2012, 29 primary spine MPNSTs were identified in 12 (41%) females and 17 (59%) males with a mean age at diagnosis of 40 ± 17 years (range 5–74 years). The median patient follow-up was 1.3 years (range 42 days to 11.2 years). In total, 14 (48%) patients died and 14 (48%) patients suffered a local recurrence, 10 (71%) of whom died. Within 2 years after surgery, the median survival and local recurrence were not achieved. Data about Enneking appropriateness of surgery were available for 27 patients; 9 (33%) underwent an EA procedure and 18 (67%) underwent an EI procedure. Enneking appropriateness did not have a significant influence on local recurrence or survival. Twenty-two patients underwent adjuvant treatment with combined chemo- and radiotherapy (n = 7), chemotherapy alone (n = 3), or radiotherapy alone (n = 12). Adjuvant therapy had no significant influence on recurrence or survival. CONCLUSIONS The rates of recurrence and survival were similar for spinal MPNSTs regardless of whether patients had an EA or EI resection or received adjuvant therapy. Other factors such as variability of pathologist interpretation, PET CT correlation, or neurofibromatosis Type 1 status may play a role in patient outcome. Nonetheless, MPNSTs should still be treated as sarcomas until further evidence is known. The authors recommend an individualized approach with careful multidisciplinary decision making, and the patient should be informed about the morbidity of en bloc surgery when considering MPNST resection.