Abstract 85P
Background
Solitary fibrous tumour (SFT) is an uncommon soft-tissue sarcoma that can appear in any location, most commonly in the pleural surfaces. The presence of anomalous fusion genes between NAB2 and STAT6, with a high nuclear expression of STAT6 is characteristic. Although indolent, there is a small risk of long-term relapses and dedifferentiation to more aggressive disease.
Methods
Retrospective review of 56 patients diagnosed with SFT (2000-2023); clinical and pathological basal data, primary treatment, local and systemic relapses, treatment used for advanced disease and long-term overall survival (OS).
Results
56 patients (pts), 60% female. Median age 55 years (13-78). Location: 38% pleura, 15% lung, 11% lower limbs, 6% orbit, 6% subcutaneous; other < 5%. 5 patients (9%) with metastasis at diagnosis, all high-grade. Primary treatment: surgery in 83% (R0 resection 89%), watchful waiting (WW) in 11%. 1 pt with adjuvant radiotherapy. 4 pts treated with surgery (7%) had a local relapse; median time to relapse was 78 months (19-204). 3 of the 4 pts treated with WW (5%) had a local relapse, median time to relapse of 78 months (70-108). All 8 pts were rescued surgically. 3 systemic relapses (3%), again in high-grade tumours. 1st systemic treatment in 8 pts: anthracycline-based CT in 2 pts (3%, partial response in both), immunotherapy-antiangiogenic therapy in 2 pts (3%, stable disease in both) and pazopanib in 5 pts (9%, 1 partial response, 2 stable diseases 2 progressions). 4 pts with 2nd line CT and 2 pts with 3rd line CT. Disease control were poor with rapid progression. Median follow-up of 70 months (6-204), median OS 167 months (6-204 months); 86% remain free of disease, 9% alive with active disease and 5% deaths due to progression.
Conclusions
SFT is a heterogenous disease that can appear in any anatomical location and in a wide age range. Most patients can be treated surgically with good long-term results and salvage surgery is feasible in most cases of local relapse, with no need of adjuvant therapy. Unfortunately, distant metastases, although infrequent, are more difficult to treat. Targeted therapy such as pazopanib and immunotherapy show promising results. It is hoped that knowledge on the molecular drivers in SFT could show us potential targets for future therapies.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.