Enrico Martin

291 SUMMARY MPNSTs are rare soft tissue sarcomas (STS) that undergo aggressive treatment including resections with wide margins. Histotype-specific treatment and outcomes of MPNSTs have been studied infrequently. In contrast to other STS, resecting MPNSTs always requires the resection of nervous tissue making them prone to loss of function. Part I Oncological Outcomes and Treatment of MPNST In Part I, we elaborated on treatment differences, oncological outcomes, and risk factors of worse survival in MPNSTs. Although MPNSTs are rare, they may occur at any anatomical site that harbors peripheral nerves. Additionally, because of their origin in nervous tissue and the existence of benign counterparts that resemble malignancy, various surgical subspecialties may encounter and treat MPNSTs. Chapter 2 Treatment and Survival Differences per Tumor Site Several studies have reported differences in survival based on MPNST tumor site, however some tumor sites are rare and have been difficult to investigate on a larger scale. The SEER database, an American cancer registry, provided us the largest population to date including 3267 MPNST patients. Using this data we observed that treatment and outcomes vary according to tumor site. In concordance to previous studies worse survival was seen in patients with central tumors or tumors of the head and neck. Surprisingly, intracranial MPNSTs had a better prognosis. Also, children seemed to have a better prognosis compared to adults when controlling for several confounders. Furthermore, older age (60+), male gender, black race, high grade, and large tumors were associated with worse survival. Chapter 3 Treatment and Survival in the Netherlands Patients from the Dutch Cancer Registry were obtained to investigate treatment of MPNST in the Netherlands in a nationwide unselected cohort of patients. Because MPNSTs are difficult entities to diagnose pathologically, we also obtained all pathological reports related to these patients from the Dutch National Pathology Database to exclude uncertain diagnoses and obtain information on NF1 status which is not available in the Dutch Cancer Registry. In this study we excluded pediatric and metastatic patients at diagnosis as these are generally treated differently. A total of 629 MPNST patients were analyzed and stratified between retroperitoneal and non-retroperitoneal MPNST. This has rarely been done, but may be important, because we know that retroperitoneal soft tissue sarcomas (STS) are clinically more aggressive tumors. Retroperitoneal MPNSTs were more commonly unresectable and in resected cases radiotherapy was administered less frequently, but chemotherapy more frequently. We observed that in localized non-retroperitoneal adult MPNST, older age (60+), presence of NF1, irresectable, large, and deep-seated tumors were associated with worse survival. A