Malignant peripheral nerve sheath tumors (MPNST) – Clinicopathological study and treatment outcome of twenty-four cases

BACKGROUND: Malignant peripheral nerve sheath tumor (MPNST) is biologically an aggressive tumor for which the treatment of choice is the surgery. We reviewed the clinical profile, diagnostic methods, treatment patterns, and outcome of twenty-four MPNST patients in this study. PATIENTS AND METHODS: A retrospective analysis of 24 MPNST patients, treated from 1994 to 2002, in the department of Surgical Oncology at All India Institute of Medical Sciences, New Delhi, was done. A combination of gross, histopathological and immunohistochemical findings, and proliferation markers (MIB1) were considered for diagnosis and grade of the MPNST. Survival analysis was done by the Kaplan-Meier method and differences were evaluated with the log-rank test. Multivariate analysis was carried out by using Cox's proportional hazards model by using SPSS (Version 9, Chicago, Illinois) software. RESULTS: MPNST constituted 12% of all soft tissue sarcomas, where 21% (5/24) of patients had associated Von Recklinghausen's disease (VRHD). A higher incidence of male preponderance and multifocal MPNST were noted in the present series. At a mean follow-up of 38 months, 13 (54 %) patients had relapse of disease and 5-year over all and disease free survival were 58% and 35% respectively. In univariate analysis, sex (p = 0.05), tumor depth (p < 0.03), and cellular differentiation (p < 0.002) were shown to be adverse prognostic factors for disease free survival and sex (p = 0.04), cellular differentiation (p < 0.0004), and tumor grade (p = 0.05) for overall survival. However, in multivariate analysis, cellular differentiation (p < 0.005) and tumor grade (p < 0.01) emerged as independent prognostic factors for both disease free and overall survival, respectively. Postoperative radiotherapy (RT) has shown a definite role in both disease free and overall survival in this study. CONCLUSION: MPNSTs constituted a significant proportion (12%) of soft tissue sarcoma in our medical center. Heterogeneous differentiation and multifocality of the tumor were few distinct features of MPNST. Sex and cellular differentiation were noticed as the new adverse prognostic factors and adjuvant radiotherapy has been proved to be a significant treatment tool in the current series.