Effectiveness of Classification and Scoring Systems in Solitary Fibrous Tumor Prognosis Prediction

Objectives Because thoracic solitary fibrous tumors (SFTs) are rare, there is limited information on their clinical features, treatment, and follow-up. The literature mainly comprises individual case reports. Definitions, classifications, and scoring systems have been created to predict their clinical behaviour. Our study aimed to analyse SFT data to identify prognosis-related factors and to compare the performance of two describing approaches and three risk stratification models. Methods Medical data from 37 patients, including 32 patients with SFT aged 18 years and older who underwent surgical treatment and five patients diagnosed by biopsy between 2004 and 2024, were analysed retrospectively. Parameters affecting recurrence and survival were investigated, and the effectiveness of existing classification and scoring systems was compared. Results Factors potentially associated with recurrence included four or more mitoses (10 HPF) (p = 0.023), necrosis (p = 0.007), at least 10% Ki-67 positivity (p = 0.012), malignancy (p = 0.046), and tumor size (p = 0.022). Relapses were observed only in the malignant group according to the England classification (p = 0.046), only in stage 3 according to the de Perrot classification (p = 0.161), only in those with scores of three or higher according to the Tapias classification (p = 0.036), only in those with scores of two or higher according to the Diebold classification (p = 0.021), and all in high-stage groups (p = 0.001) according to the Demicco classification. All recurrences occurred at significant or high scores. Conclusions The factors directly affecting prognosis include malignancy, a mitotic count of 4 (10 HPF) or higher, necrosis, recurrence, and ki-67 ≥ 10%, while indirectly influencing prognosis are increasing age, increasing size, and pleomorphism. For malignancy criteria, England's standards should be used, and de Perrot's classification is partly helpful. The Tapias, Diebold, and Demicco scoring systems are highly effective in predicting recurrence and prognosis. However, the modified Demicco system is more advantageous and offers a higher level of assessment.