Enrico Martin

62 Chapter 3 treatment regimens. 5,23 Age has been reported as an independent predictor in one cohort only. 5 A study using registry data from the Surveillance, Epidemiology, and End Result (SEER) database also showed a significant correlation in which pediatric cases had the best prognosis, while older patients did significantly worse. 24 Larger tumor size has repeatedly been reported to affect survival, 2–5,21,22,25 while tumor depth has only been shown an independent predictor of survival in one study. 10 Tumor site has been reported varyingly as a predictor of survival, where truncal location, and in some series head and neck MPNSTs were independently associated with worse survival compared to extremity sites. 3–5,22,24,26 In this study, this correlation was not found, but results from other studies may be impeded as retroperitoneal cases were not evaluated as separate entities. The finding of a trend for MPNSTs encased by neurofibromas having a better survival compared to de novo tumors, despite the largest proportion being NF1 patients, may possibly be explained by tumor grade. 27 However, an exact explanation could not be found in this study and is therefore of interest in future studies. Table 3 Common independent predictors of survival in previous large cohort studies. Study N 5-year OS Factors influencing survival a Age NF1 Size Depth Site R2 Current study b 594 50.8% + + + + - + Miao 2019 b 251 56.5% + + + NA + + Yuan 2017 b 140 45.0% - - - - - NA Valentin 2016 b 294 59.4% - - - + - + Watson 2016 c 289 52.0% - - - - + + Fan 2014 146 57.0% - - - - - - LaFemina 2013 c 105 NR - - + NA - + Stucky 2012 c 175 60.0% - - + - + - Porter 2009 123 51.0% NA + + - - NA Zou 2009 c,d 140 38.7% - - + NA - NA Anghileri 2006 b,c 205 39.9% - - + NA + + Carli 2005 e 167 51.2% - + + NA + NA Wong 1998 b 134 52.0% NA - - NA - + a : significantly associated (+), not significantly associated (-), not evaluated (NA), b : localized disease only, c : analyses on disease-specific survival, d : multivariate analyses on completely resected cases only, e : includes pediatric cases only, N: number of patients, NF1: neurofibromatosis type 1, OS: overall survival Treatment of localized MPNST Macroscopically positive surgical margins have repeatedly been shown to have a strong correlation with poor survival in other series as well. 4,5,10,25,26,28 The conditional inference tree showed that it was even the strongest predictor for survival in localized disease. While R1 resections are not associated with worse prognosis, radiotherapy may be indicated to reduce the risk for local recurrence. 3,11,12 In both retroperitoneal as well as non-retroperitoneal MPNSTs, close margins may achieve similar survival outcomes, yet