Prognostic usefulness of a modified risk model for solitary fibrous tumor that includes the Ki-67 labeling index

Shintaro Sugita,Tomomi Kido,Yukinori Akiyama,Keiko Segawa,Makoto Emori,Tomoko Takenami,Noriaki Kikuchi,Tadashi Hasegawa,Shiro Hinotsu,Kohichi Takada

doi:10.1186/s12957-022-02497-2

Shintaro Sugita, Tomomi Kido + Show 8 more

Open Access

https://doi.org/10.1186/s12957-022-02497-2

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Abstract

BackgroundPredicting the prognosis of patients with solitary fibrous tumor (SFT) is often difficult. The prognostic risk models developed by Demicco et al. are now the standard for evaluating the risk of SFT metastasis in the current World Health Organization classification of soft tissue and bone tumors.MethodsIn this study, we examined the prognostic usefulness of a modified version of the Demicco risk models that replaces the mitotic count with the Ki-67 labeling index. We compared the three-variable and four-variable Demicco risk models with our modified risk models using Kaplan–Meier curves based on data for 43 patients with SFT.ResultsWe found a significant difference in metastasis-free survival when patients were classified into low-risk and intermediate/high-risk groups using the three-variable (P = 0.022) and four-variable (P = 0.046) Demicco models. There was also a significant difference in metastasis-free survival between the low-risk and intermediate/high-risk groups when the modified three-variable (P = 0.006) and four-variable (P = 0.022) models were used.ConclusionModified risk models that include the Ki-67 labeling index are effective for prediction of the prognosis in patients with SFT.

Highlights

The current World Health Organization (WHO) classification of soft tissue and bone tumors defines solitary fibrous tumor (SFT) as a rarely metastasizing intermediate malignant tumor showing fibroblastic/myofibroblastic differentiation [1]
Evaluation of mitotic figures tends to differ among observers [8], we have developed a grading system that uses the Ki-67 labeling index (LI) instead of the mitotic count in order to provide a more universal grading system for predicting the prognosis of soft tissue sarcoma [9,10,11,12]
The mean follow-up duration was 63 months, at the end of which 32 patients were alive without local recurrence or metastasis

Summary

Introduction

The current World Health Organization (WHO) classification of soft tissue and bone tumors defines solitary fibrous tumor (SFT) as a rarely metastasizing intermediate malignant tumor showing fibroblastic/myofibroblastic differentiation [1]. Predicting the prognosis of SFT is often difficult. The majority of SFTs have morphologically bland features and a benign clinical course. Some SFTs with morphologically benign features have a fatal outcome. It can be difficult to predict the prognosis of SFT based on histological parameters alone. Predicting the prognosis of patients with solitary fibrous tumor (SFT) is often difficult. The prognostic risk models developed by Demicco et al are the standard for evaluating the risk of SFT metastasis in the current World Health Organization classification of soft tissue and bone tumors

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