Dermatofibrosarcoma Protuberans with Fibrosarcomatous Transformation

Voth et al:
- Performed an extensive review of the literature and found 157 patients with DFSP with fibrosarcomatous transformation:
  - Local recurrence was significantly lower:
    - With margins ≥ 2 cm compared with those with undefined margins:
      - 20% vs. 39%, p=0.01
A deep margin in the surgical management of DFSP is considere adequate:
- If it remains intact because the deep layer of the muscular fascia acted as an anatomic boundary
There are no data to suggest a benefit from radiation therapy:
- If the margins are adequate:
  - Even in patients with close or unknown surgical margins:
    - The benefit is inconclusive
Of the 33 patients reported by Voth et al who received adjuvant radiation therapy because of concerns related to the margins:
- 12 (36.4%) still had local recurrences
- Five (15.2%) developed metastases
- Three (9%) had both
Voth et al noted distant metastases:
- In 21 of 157 patients (13.4%):
  - Which is higher than the less than 5% rate in ordinary DFSP
- However, no data have shown benefit of adjuvant imatinib for DFSP:
  - Although the response rate among unresectable locally advanced or metastatic tumors approaches 50% in patients with the t(17;22) mutation
- Imatinib therapy:
  - May be considered to downstage unresectable tumors or prior to re-excision for those with tumor-positive margins
- Although doxorubicin is considered the single most active agent in soft tissue sarcoma:
  - There is no evidence of its efficacy in DFSP
References:
- DuBay D, Cimmino V, Lowe L, Johnson TM, Sondak VK. Low recurrence rate after surgery for dermatofibrosarcoma protuberans: a multidisciplinary approach from a single institution. Cancer. 2004;100:1008-1016.
- Leahy M, Garcia Del Muro X, Reichardt P, et al. Chemotherapy treatment patterns and clinical outcomes in patients with metastatic soft tissue sarcoma. The Sarcoma treatment and Burden of Illness in North America and Europe (SABINE) study. Ann Oncol. 2012;23:2763-2770.
- Rutkowski P, Dƒôbiec-Rychter M, Nowecki Z, et al. Treatment of advanced dermatofibrosarcoma protuberans with imatinib mesylate with or without surgical resection. J Eur Acad Dermatol Venereol. 2011;25:264-270.
- Voth H, Landsberg J, Hinz T, et al. Management of dermatofibrosarcoma protuberans with fibrosarcomatous transformation: an evidence-based review of the literature. J Eur Acad Dermatol Venereol. 2011;25:1385-1391.