Extrameningeal solitary fibrous tumors—surgery alone or surgery plus perioperative radiotherapy: A retrospective study from the global solitary fibrous tumor initiative in collaboration with the Sarcoma Patients EuroNet

Abstract

Background Solitary fibrous tumor (SFT) is a rare mesenchymal malignancy. Although surgery is potentially curative, the local relapse risk is high after marginal resections. Given the lack of prospective clinical trial data, the objective of the current study was to better define the role of perioperative radiotherapy (RT) in various SFT presentations by location. Methods This was retrospective study performed across 7 sarcoma centers. Clinical information was retrieved from all adult patients with extrameningeal, primary, localized SFT who were treated between 1990 and 2018 with surgery alone (S) compared with those who also received perioperative RT (S+RT). Differences in treatment characteristics between subgroups were tested using analysis of variance statistics and propensity score matching. Local control and overall survival rates were calculated from the start of treatment until progression or death from any cause. Results Of all 549 patients, 428 (78%) underwent S, and 121 (22%) underwent S+RT. The median follow‐up was 52 months. After correction for mitotic count and surgical margins, S+RT was significantly associated with a lower risk of local progression (hazard ratio, 0.19: P = .029), an observation further confirmed by propensity score matching (P = .012); however, this association did not translate into an overall survival benefit. Conclusions The results from this retrospective study investigating perioperative RT in patients with primary extrameningeal SFT suggest that combining RT with surgery in the management of this patient population is significantly associated with a reduced risk of local failures, especially in patients who have less favorable resection margins and in those who have tumors with a high mitotic count.

Soft tissue and visceral sarcomas: ESMO–EURACAN–GENTURIS Clinical Practice Guidelines for diagnosis, treatment and follow-up☆

“…24 Histological types such as MLS, solitary fibrous tumour (SFT), myxofibrosarcoma, and extraskeletal myxoid chondrosarcoma (EMC) gain the greatest benefit from RT. 25,26 For MLS, one study has recently investigated a low dose (18x2 Gy),…”

“…RPS that could be surgically converted by downsizing, and in chemosensitive histologies such as synovial sarcoma. 26 Preoperative RT in resectable tumours did not improve RFS and OS in one randomised clinical trial [I, D]. 65 should not be considered.…”

“…However, the activity of RT in SFT should be factored into the decision. 26 For all other histological types an individualised decision with a higher degree of uncertainty can be made based on size of the tumour, its local risk and the expected quality of surgery.…”

Solitary Fibrous Tumor in the Perianal Region: Report of Two Cases With an Atypical Location

“…In another retrospective study published in July 2020, preoperative and postoperative radiotherapy were compared, with no evidence of significant differences. However, in the local control, benefits of perioperative radiotherapy were observed, without affecting overall survival, mainly in those with less favorable resections and greater mitotic activity [14].…”

Solitary Fibrous Tumor: Molecular Hallmarks and Treatment for a Rare Sarcoma

“…Based on the Demicco risk stratification, patients with intermediate-to high-scoring tumors have a high risk of recurrence. A recent international retrospective cohort of patients with non-meningeal SFTs demonstrated, using propensity score matching for margin status and mitotic count, that oncologic resection and radiotherapy (50 Gy; neoadjuvant or adjuvant) significantly reduced the risk of local recurrence compared with oncologic resection alone [34]. There was no difference in overall survival between the two groups.…”