Predictors of Recurrence and Survival in Malignant Triton Tumours: A Case Report and Systematic Review Systematic Review of Malignant Triton Tumours

Abstract Background: Malignant triton tumours (MTTs) are a rare and aggressive subset of malignant peripheral nerve sheath tumours (MPNSTs). A systematic review was conducted to better understand the prognosis and prognostic factors of this tumour in adult patients, and to provide treatment guidance for clinicians encountering this rare tumour. Methods: A PubMed search was conducted using the keywords “rhabdomyoblastic,” “rhabdomyosarcomatous,” “triton,” “case series” and “case report”. A reference list search was also completed. Two independent investigators completed abstract and full-text reviews. Articles were restricted to peer-reviewed articles in English language only containing adult MTT cases (≥ 18 years), and excluding articles with insufficient treatment/outcome data. Univariable and multivariable Cox proportional hazards regression was performed to identify significant predictors of overall survival (OS) and progression-free survival (PFS). Results: A total of 123 cases from the literature and 1 case from our institution were included in the final analysis. The 2-year and 5-year OS was 46.2% and 32.2%, and the 2-year and 5-year PFS was 27.1% and 21.3%, respectively. On multivariable analysis for OS, prior radiation exposure (hazard ratio [HR]: 3.99, p = 0.027), central nervous system or spine disease site (HR: 5.86, p < 0.001) and positive neurofibromatosis 1 (NF1) status (HR: 3.42, p < 0.001) were associated with worse survival. Adjuvant radiotherapy (HR: 0.58, p = 0.038) was associated with improved survival. Positive NF1 status (HR: 2.34, p < 0.001) and positive margins (HR: 3.28, p < 0.001) were associated with worse PFS. Conclusion: MTTs are rare and have poor long-term survival. Negative surgical margins and adjuvant radiation were found to be associated with improved outcomes.