Abstract 86P
Background
DFSP is a rare uncommon disease with scarce literature, especially in developing countries. In India, expert diagnosis by a sarcoma pathologist is available, but mainly in tertiary care centres (molecular testing is not available).
Methods
Based on expert histopathology, we analysed the database of patients with DFSP who presented to the sarcoma clinic from January 2016 to December 2023. We have included all cases of locally advanced or metastatic DFSP. The dose of imatinib depended on the physician’s discretion, clinical response and the patient's tolerance.
Results
A total of 38 patients, with a median age of 36 years (range: 19-76 years) with male preponderance 25 patients (65%). All cases were diagnosed based on histopathology alone, by experts at a tertiary-level hospital. The most common primary site is the trunk and the metastatic site is the lung. The time from baseline diagnosis to development of metastasis is 23 months with a standard deviation of 43 months. Our patients had undergone a median of two surgeries (range: 0-4 surgeries) and 14 cases (36%) had received radiotherapy Among the 21 DFSP cases, 2 has complete response (CR), 5 has partial response (PR), 6 has stable disease (SD) with imatinib 400mg and 8 pts experienced disease progression (PD) while on imatinib. Thus, the overall disease control achieved with imatinib is 62% (13/21). The median PFS post imatinib treatment was 8 months (95% CI, 1-72 months). The overall median OS was 84 months (range: 21 - 168). Eight cases who had progressive disease on imatinib, two were lost to follow and 6 were tried with increased doses of imatinib (600mg or 800 mg doses) for later progression and were treated with dacarbazine, pazopanib, sorafenib, cabozantinib and doxorubicin.
Table: 86P
| CHARACTERISTICS | n-38 | % |
| FS variant | 22 (14 has metastatic disease) | 57.8 |
| Site | ||
| Trunk | 15 | 39.5 |
| Abdominal wall | 11 | 29 |
| Scalp | 5 | 13 |
| Shoulder | 4 | 10 |
| Others | 3 | 7.8 |
| Metastatic site | ||
| Lung only | 6/17 | 35 |
| Lung with other sites | 11/17 | 64.5 |
| Locally advanced/unresectable | 21 | 55 |
Conclusions
In the absence of translocation studies, diagnosis based on expert histopathology may help in targeted therapy-based treatment. The fibrosarcomatous variant has a worse prognosis, and further research is a must in this subset.
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.