Enrico Martin

31 Treatment and survival differences across tumor sites 67 mm (IQR: 37-100 mm). The largest tumors were found in core (median 80 mm, IQR: 60-115 mm) and limb sites (70 mm, IQR: 40-100 mm), whereas intracranial (37.4 mm, IQR: 17.3-43.5 mm), spinal (39.5 mm, IQR: 20-60 mm), and head & neck sites (38 mm, IQR: 20-65 mm) were relatively smaller in size. Treatment modalities Most patients were treated with surgery (46.8%) which was followed by radiotherapy in 32.8% of patients. Intracranial tumors were less frequently resected (58.1%), whereas spinal tumors were treated surgically in 83.0% of cases. Gross total resection (GTR) was only achieved in 28.0% of cases and 30.0% of surgeries resulted in a subtotal resection ( Table 2 ). GTR was most often achieved in spinal tumors (42.6%) and least frequently in core tumors (24.9%). Overall, 38.9% of patients were subjected to a form of radiation, and percentages varied slightly from 35.5% of intracranial cases to 41.8% of cases in extremities. Radiotherapy was given in a neoadjuvant setting in 4.2% and adjuvant in 28.0% of all cases. Preoperative radiation was most often used in limb sites (6.8%). Intraoperative radiation was administered in only 0.6% of cases. A combination of both pre- and postoperative radiotherapy was only given in 0.8% of all cases. Univariable and multivariable analyses Univariable analysis for intracranial MPNSTs showed that older age (>60 years), surgical procedure in the form of a biopsy, and larger size are associated with decreased survival (all p<0.05, Supplemental Table 3 ). In multivariable analyses, older age and larger size were significantly associated with decreased survival even after correction for multiple testing. In univariable analysis for spinal tumors, treatment strategies that included radiation and larger size are associated with worse survival (p<0.05 for both). Larger size lost significance in multivariable analyses. Treatment with radiotherapy only was significantly associated with worse survival even after Bonferroni correction. Older age, higher tumor grade (grade ≥3), and large size are associated with higher mortality in head and neck tumors (all p <0.05) in univariable analysis. These factors were still associated with poorer survival in multivariable analyses and correction for multiple testing. Older age, expectant management or radiation solely, large size, and higher grade are associated with higher mortality in limb tumors (all p<0.05, Supplemental Table 4 ) in univariable analysis and multivariable analyses with Bonferroni correction. Similar characteristics were associated with decreased survival in core MPNSTs. In the latter, patients that received radiation after surgery seemed to have a better overall survival in univariable analysis. In multivariable analyses older age, high tumor grade, large size, treatment modalities without surgery were all still significantly associated with worse overall survival, even after Bonferroni correction. Pediatric cases and those that received radiotherapy after surgery had an increased survival in multivariable analyses, but this was no longer significant after correction for multiple testing. In multivariable analysis of all primary MPNST cases, pediatric cases and intracranial 2