The Approach to Solitary Fibrous Tumors: Are Clinicopathological Features and Nomograms Accurate in the Prediction of Prognosis?

Introduction. Currently, factors such as size, mitotic rate, and degree of necrosis have been shown to influence survival in patients with solitary fibrous tumors (SFTs); however, there remains no consensus regarding the associations between tumor characteristics and the malignant nature of these tumors. The aim of this article was to identify factors that would help in prognosticating SFTs and to validate the MD Anderson Cancer Center (MDACC) SFT nomogram in the largest known series of SFTs treated in an Asian population. Methods. A retrospective review of all patients with a diagnosis of SFT treated surgically in our institution between 2005 and 2015 was carried out. Basic demographics, clinicopathological, and surgical factors were analyzed for association with clinical outcomes. Factors that predicted for distant recurrence (DR) and poor survival were identified as high-risk features. The MDACC nomogram was validated by assessing the extent of discrimination, quantified using Harrell’s concordance index (C-index). Results. Fifty-nine patients were included in analysis. Significant univariate associations for DR were found for mitotic rate (P = .05) and presence of necrosis (P = .04). Significant univariate associations for overall survival were found for presence of recurrence (P = .035), presence of necrosis (P = .072), and mitotic rate (P = .033). The C-index associated with the nomogram was 0.75. Conclusion. There is a negative association for DR and overall survival, with the mitotic rate and presence of necrosis. We propose that SFTs with these features should be regarded as high risk. The MDACC nomogram generally predicts well for patients in an Asian population.