Response to chemotherapy of solitary fibrous tumour: a retrospective study

To report on anthracycline-based chemotherapy in a retrospective case-series analysis of solitary fibrous tumour (SFT) patients treated within the Italian Rare Cancer Network.

We reviewed a set of SFT treated with chemotherapy since 2002, focusing on anthracycline, administered alone or in combination with ifosfamide. Responses to ifosfamide as a single agent were also evaluated. Pathologic diagnosis was centrally reviewed, distinguishing typical, malignant (MSFT) and dedifferentiated (DSFT) subtypes.

Among 42 SFT patients treated with chemotherapy, we selected 31 cases (mean age: 62 years; locally advanced/metastatic: 13/18; front-line/further line: 25/6; typical/MSFT/DSFT/not assessable: 1/17/12/1) who received anthracycline-based chemotherapy (anthracycline monotherapy: eight; anthracycline+ifosfamide: 23). 30 patients are evaluable for response. Best response by Response Evaluation Criteria in Solid Tumours (RECIST) was: partial response (PR): 6 (20%), stable disease (SD): eight (27%), progressive disease (PD): 16 (53%) cases. Responses were confirmed after 3 months. Median progression-free survival (PFS) was 4 (range 2-15) months, with 20% of patients being progression-free at 6 months. PR was found in 2/18 (11%) MSFT and 4/12 (30%) DSFT, with a median PFS of 3.5 and 5 months in MSFT and DSFT, respectively. 19 patients received high-dose prolonged-infusion ifosfamide (front-line/further line: 11/8; typical/MSFT/DSFT: 0/15/4) with two (10%) PR, five (26%) SD, 12 (63%) PD.

This retrospective series suggests that in SFT anthracyclines have a degree of antitumour activity in the range of soft tissue sarcoma chemotherapy. Ifosfamide monotherapy seemed to have lower activity. A higher response rate was observed in DSFT in comparison to MSFT. Studies on targeted therapies are ongoing.