Enrico Martin

79 Treatment and survival in pediatric MPNST 0.00 0.25 0.50 0.75 1.00 0 50 100 150 Time (months) Survival variable No NF1 NF1 A 0.00 0.25 0.50 0.75 1.00 0 50 100 150 Time (months) Survival variable 1989−2005 2006−2017 B Figure 3 Adjusted survival curves for prognostic factors in localized pediatric MPNST. A) NF1 status B) time period (1989-2005 versus 2006-2017) Survival in pediatric MPNST Historically, pediatric MPNSTs have been associated with poor prognosis, with 5-year survival rates ranging from 34.6-65%. 6,24,25 Earlier series reported even worse survival rates. 26–28 However, a trend towards increased survival in pediatric MPNST has been suggested in a study using data from the Surveillance, Epidemiology, and End Results Program (SEER) database. 29 Anthracycline-based regimens with or without additional ifosfamide have shown superior results in a large cohort of pediatric patients in a study published in 2005. 6 The European Pediatric Soft Tissue Sarcoma Group (EpSSG) consequently published results of their 2005-2016 cohort in which doxorubicin and ifosfamide was used whenever chemotherapy was administered. 15 The study by the EpSSG showed higher 5-year survival rates compared to the earlier publication of the Italian and German Soft Tissue Sarcoma Cooperative Group. This may explain at least in part the increasing survival rates observed in this study after 2005, as doxorubicin and ifosfamide use may have risen compared to other regimens since the first publication in 2005. Furthermore, in other sarcoma trials, such as the EpSSG rhabdomyosarcoma 2005 trial also showed increase in survival in both study arms, indicating that survival of sarcomas in children generally may be improving over the years. This may in turn be due to centralization of their healthcare. While survival rates in pediatric MPNST from previous studies show comparable results as in adult MPNST, 2,30,31 another study using SEER data showed that children had a better prognosis when controlling for known confounders. 4 Few other studies have found factors associated with survival in pediatric MPNST. 6,15,27 NF1 status has previously been reported as well to be independently associated with worse survival in children. 6,15,27 It is not yet completely clear what NF1-related factors cause this difference. Demographically, all but initial tumor size differed in this study between NF1 and non-NF1 patients and no differences in treatment modalities were observed, especially in final surgical margins. 4