Recurrence of Solitary Fibrous Tumor of the Pleura: A 20-Years bi-Centric Study with Risk Score Comparison.

Solitary fibrous tumors of the pleura (SFTP) are rare fibroblastic mesenchymal tumors with usually a benign histologic profile. However, 10 to 30% will recur or metastasize. Our study aimed to determine the recurrence rate of SFTP, compare the effectiveness of four major risk stratification models, and analyze recurrence risk factors. We conducted a bi-centric retrospective cohort study between 2003 and 2022 on resected SFTP. Clinical, surgical procedures and pathologic reports were examined. Patients were risk-stratified by using four prediction models: de Perrot, Tapias, modified Demicco, and G-score. We included 96 patients with 49 female (51%) and a median age of 67 years-old. Median follow-up was 6 years. Sixteen patients presented recurrence/metastasis (16,7%). The 5-years/10-years/15-years freedom from recurrence rates were 88.4%/65%/63.2%. Risk factors for recurrence were age, paraneoplastic syndrome, tumour size ≥ 10 cm, extended resection, Ki67 index ≥10%, hypercellularity, pleomorphism, necrosis, and ≥ 4 mitotic figures. The 5-years/10-years/15-years OS were 93.9%/83.4%/83.4% respectively. During follow-up, a total of 9 patients (9.3%) died with 6 related disease death (66%). Survival was significantly worse in patients with recurrence (HR = 12.5 [95% CI = 2.58 to 61.0], p < 0.0001). Comparison of the four risk stratification models revealed that the modified Demicco score was the most accurate to predict recurrence (AUC= 0.83 95% CI: 0.74-0.91). Recurrence of SFTP after surgical complete resection occurs in few patients and is associated with an increased mortality. The modified Demicco score is the most accurate to predict recurrence.