S1055
Clinical – Sarcoma, skin cancer, malignant melanoma
ESTRO 2026
performed in 3/90 (3%) patients, due to intercurrent metastatic disease. One patient also received postoperative radiotherapy (30Gy), because of a disappointing 20% pathological response and multiple microscopically positive margins in the resection specimen. LRFS, PFS, DSS and OS rates at 5 years were 98%, 81%, 90% and 89%, respectively. In total, 21% of the patients experienced a wound complication, and 16% required intervention. There were no fractures nor severe fibrosis or joint stiffness. Any grade 2 and grade 3 late toxicity was seen for 15% and 3% of patients, respectively (Table 2).
Proffered Paper 4909
Dose reduction in myxoid liposarcoma (DOREMY): long-term update of a multicenter, single-arm, phase II trial Jules Lansu 1,2 , Judith V.M.G. Bovee 3 , Petra M. Braam 4 , Aisha B. Miah 5 , Astrid N. Scholten 1 , Ovind S. Bruland 6 , Elizabeth H. Baldini 7 , Olga Hamming - Vrieze 1 , J. Heukelom 8 , Lisette M. Wiltink 9,1 , Florine Foppele 1 , Fred Ubbels 10 , Vincent van der Noort 11 , Rick L Haas 1,12 1 Radiotherapy, AvL/NKI, Amsterdam, Netherlands. 2 Radiotherapy, Institute Verbeeten, Tilburg, Netherlands. 3 Pathology, Leiden University Hospital, Leiden, Netherlands. 4 Radiotherapy, Radboud UMC, Nijmegen, Netherlands. 5 Radiotherapy, The Royal Marsden Hospital, London, United Kingdom. 6 Medical oncology & Radiotherapy, Oslo university hospital, Oslo, Norway. 7 Radiotherapy, Dana Farber / Harvard, Boston, USA. 8 Radiotherapy, MAASTRO, Maastricht, Netherlands. 9 Radiotherapy, Leiden University Hospital, Leiden, Netherlands. 10 Radiotherapy, Groningen University medical center, Groningen, Netherlands. 11 Biometrics, AvL/NKI, Amsterdam, Netherlands. 12 Radiotherapy, Leiden university Hospital, Leiden, Netherlands Purpose/Objective: Treatment of most intermediate- and high-grade soft tissue sarcomas is resection and perioperative radiotherapy, as it provides superior local control compared to surgery alone. However, preoperative radiotherapy to the standard dose of 50 Gy in 25 daily fractions is associated with morbidity such as wound complications and late toxicity, which can negatively impact quality of life. Previous data show exceptional clinical radiosensitivity of the myxoid liposarcoma (MLS) subtype. We hypothesized that dose reduction of preoperative radiotherapy for MLS would decrease morbidity without a detrimental effect on local recurrence free survival. Material/Methods: The DOREMY trial (NCT02352995) is a prospective, single-arm, phase II trial designed to assess the efficacy of 36 Gy in 18 daily fractions [1]. It was conducted in tertiary sarcoma centers in Europe and the US. Eligible patients were adults with biopsy proven and translocation-confirmed localized MLS of the trunk or extremity. In this final analysis we report long-term local recurrence free survival (LRFS), progression free survival (PFS), disease specific survival (DSS), overall survival (OS) and late toxicity. Results: Ninety patients were enrolled between November 24, 2010 and May 14, 2020. The baseline characteristics are summarized in Table 1. Median follow-up was 66 months. Preoperative radiotherapy was delivered according to protocol in all patients. Surgery was not
Conclusion: Mature data of the DOREMY trial demonstrate excellent local control and a low-toxicity profile following dose reduction of preoperative radiotherapy in MLS. These compelling phase II findings are in line with the promising preliminary data of the LIPOMYX trial [2]. Therefore, this regimen could be considered as an appropriate treatment option through shared decision-making with the patient, given the impracticality of conducting a phase III trial in a rare cancer.
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