Dermatofibrosarcoma protuberans in children and adolescents: Primary and Relapsed disease—Experience of the Cooperative Weichteilsarkomstudiengruppe (CWS). Issue 2 (19th May 2020) - Krewer, Julia
Abstract: Background: Dermatofibrosarcoma protuberans (DFSP) is a rare low‐grade tumor. Little is known about best treatment of primary and relapsed disease (RD). Methods: Treatment and outcome of 40 patients with DFSP prospectively registered within the CWS‐96 and ‐2002P trials and the registry SoTiSaR (1996‐2016) were analysed. Results: Median age was 8 years (range, 0.64‐17.77). Fluorescence in situ hybridization analysis to detect COL1A1‐PDGFB fusion genes was positive in 86% (12/14) of evaluated patients. Primary resection was performed in all patients. Patients had IRS group I ( n = 28), II ( n = 9), and III ( n = 2); not available ( n = 1). To achieve complete remission (CR), a secondary resection was performed in 18 patients resulting in microscopically complete (R0, n = 34/40) and microscopically incomplete (R1, n = 5/40) resection. All patients achieved CR. The 5‐year event‐free survival (EFS) and overall survival was 86% (±12; CI, 95%) and 100% (±0; CI, 95%), respectively. R0 resection/IRS I was significantly favorable for the 5‐year EFS. Local relapse occurred after a median time of 1.1 years (range, 0.04‐5.1) in 15% (6/40) after CR. All patients with RD underwent resection and achieved CR. Three patients had fibrosarcomatous DFSP, two were alive after R0 resection. Conclusion: Complete surgical resection is mandatory to prevent relapse of DFSP.