The Role of Radiotherapy in Malignant Peripheral Nerve Sheath Tumors: A Multicenter Cohort Study
Christianne Y.M.N. Jansma, BSc1, J. Henk Coert, MD PhD1, Dirk J Grunhagen, MD, PhD2, Cornelis Verhoef, MD, PhD3, Enrico Martin, MD, PhD4 and Walter Taal, MD, PhD3, 1University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2Erasmus Medical Center, Rotterdam, Netherlands, 3Erasmus Medical Center, Rotterdam, Zuid-Holland, Netherlands, 4UMC Utrecht, Utrecht, Utrecht, Netherlands
Introduction: Malignant Peripheral Nerve Sheath Tumors (MPNSTs) are rare and aggressive malignant soft-tissue sarcomas (STS), with 40% associated with neurofibromatosis type 1 (NF1). Surgical excision is the primary treatment for localized disease, but MPNSTs have a high likelihood of local recurrence (LR). Radiotherapy (RT) is increasingly used to improve local control in STS without affecting survival. However, its use is controversial due to the potential for higher major wound complications and increased risk of secondary malignancies in NF1 patients, as MPNSTs commonly arise from plexiform neurofibromas. This study evaluates the use of RT in these rare tumors and tries to understand its impact in local control, especially in the NF1 setting.
Material & Methods: Surgically treated primary MPNSTs from 1988 to 2019 in the MONACO multicenter cohort were included. Demographic and treatment differences, specifically the use of RT, between NF1 and non-NF1 cases were analyzed. Univariate and multivariable logistic regression analyses identified factors associated with RT utilization. Multivariate Cox regression analyses identified factors associated with LR in NF1 patients.
Results: A total of 516 patients (32.6% NF1) were included, with 149 (28.9%) developing LRs. RT was administered to 54.5% of patients (56.0% in NF1). Among them, 26.0% received neoadjuvant RT, and 79.2% adjuvant RT. Treatment modalities were similar between patients with and without NF1. Multivariable regression analysis showed high-grade tumor as the only independent factor associated with RT utilization. RT use in NF1 did not alter after correcting for tumor-, patient- and surgical factors. RT did not impact overall survival in sporadic and NF1-associated MPNST. In NF1 patients, a microscopically positive margin (R1) (HR 2.2; 95% CI, 1.21-3.91) was the only independent risk factor for LR development. After adjusting for tumor-, patient-, and surgical-related factors, the use of RT was not associated with lower rates of LR, in contrast to the sporadic population.
Conclusions: RT is commonly used in MPNST treatment regardless of its origin in NF1. While it may affect LR rate in sporadic patients, its impact in NF1 patients is less clear. Further studies are needed to evaluate its role and indications in NF1 associated MPNST.
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