Enrico Martin

61 Treatment and survival in the Netherlands Discussion Using a large nationwide unselected group of MPNSTs several patient-, tumor-, and treatment-related prognostic factors were identified. In localized non-retroperitoneal MPNST, older age, presence of NF1, and large, deep-seated tumors are patient- and tumor-specific factors significantly associated with poor survival. Resectability is the most important predictor for survival. In retroperitoneal MPNSTs, older age, male sex, and R2 or absence of surgery were associated with poor survival. There was no statistically significant difference in survival between R1 and R0 resections in both retroperitoneal and non-retroperitoneal localized MPNSTs. Figure 6 Cox proportional hazard model for overall survival in localized retroperitoneal adult MPNSTs. C-statistic: 0.811, N: number of patients, NA: not available Tumor and patient-specific predictors of survival in MPNST Factors independently found to be associated with overall survival in this study have been variously reported in other series. Whether or not presence of NF1 is inherently associated with worse survival compared to their sporadic counterparts has been subject to debate. While a meta-analysis contradicted this correlation when performing univariate analyses of series published after 2000, 20 our cohort and three other recent large series still reported this correlation when accounting for other confounders ( Table 3 ). 5,21,22 Tumor biology between NF1 and sporadic MPNST may differ significantly and further studies are needed on how to translate these differences into optimal 3