Enrico Martin

54 Chapter 3 Results Patient population A total of 875 patients were registered in the NCR database, of which 784 had a definitive pathological diagnosis of MPNST during the study period (from 1989-2017) ( Table 1 ). There was a slight male predilection (53.7%) and 26.8% of all patients were known to have NF1. On average patients were 49 years old, and NF1 patients tended to be younger (mean: 39.8±18.0) compared to non-NF1 patients (mean: 52.4±21.3, Figure 1 ). Most tumors were large (>5cm, 67.9%) and deep-seated (75.2%). Most MPNSTs arose in truncal sites (45.2%) of which 43 (5.5%) were situated retroperitoneal. In 72 cases (9.2%), the pathology report described the presence of MPNSTs within preexistent neurofibromas. Triton tumors made up 6.1% of all MPNSTs. In 11.5% of all cases, patients presented with synchronous metastases. Table 1 Clinicopathologic characteristics of study population. Variable Overall Number of patients 784 Age (years) 0-18 70 (8.9%) 19-59 434 (55.4%) 60+ 280 (35.7%) Mean (SD) 49.0 (±21.2) Male gender 421 (53.7%) NF1 210 (26.8%) Site Extremities 303 (38.6%) Trunk 312 (39.8%) Retroperitoneum 43 (5.5%) Head & Neck 100 (12.8%) NOS 26 (3.3%) Tumor size ≤5cm 190 (32.1%) >5cm 402 (67.9%) NA 192 Tumor depth Superficial 139 (24.8%) Deep 421 (75.2%) NA 224 Triton tumor 48 (6.1%) Within neurofibroma 72 (9.2%) Synchronous metastasis 90 (11.5%) Time period 1989-2005 454 (57.9%) 2006-2017 330 (42.1%) Cm: centimetre, NA: not avalaible, NF1: neurofibromatosis type 1, NOS: not otherwise specified