S1033
Clinical – Sarcoma, skin cancer, malignant melanoma
ESTRO 2026
Hippocratio General Hospital, National and Kapodistrian University of Athens, Athens, Greece. 5 Department of Orthopedic Surgery, Agios Savvas Anticancer Hospital, Athens, Greece. 6 2nd Department of Internal Medicine, Oncology Unit, Attikon University Hospital, Athens, Greece. 7 1st Department of Pathology, Medical School, National and Kapodistrian University of Athens, Athens, Greece. 8 Medical Physics Lab., School of Medicine, National and Kapodistrian University of Athens, Athens, Greece Purpose/Objective: Soft tissue sarcomas (STS) are characterized by a relatively low α / β ratio (approximately 4–5 Gy), suggesting potential radiobiological sensitivity to hypofractionation [1]. This study aimed to assess the feasibility, safety, and early oncological outcomes of moderately hypofractionated preoperative radiation therapy (RT) for extremity and superficial trunk STS within an institutional prospective phase II protocol. Material/Methods: Between 2023 and 2024, twenty patients with primary, resectable STS of the extremities or superficial trunk were prospectively enrolled. RT was delivered preoperatively to a total dose of 42.75 Gy in 15 fractions over three weeks. Surgery was planned approximately 6–10 weeks after RT completion. No concomitant chemotherapy was administered; 2 patients (10%) received neoadjuvant systemic therapy after RT. Clinical, pathological, and toxicity data were prospectively collected. Side effects were graded according to Common Terminology Criteria for Adverse Events. All specimens were analyzed by an experienced sarcoma pathologist [2]. Pathologic response was evaluated by the percentage of viable tumor cells in the resected specimen [3]. Major wound complications (MWC) were defined as wound events requiring secondary intervention within 120 days post-
Conclusion: This first regional experience from Oman demonstrates that LRT is feasible, safe, and effective in bulky sarcomas. It achieved symptom relief and radiologic necrosis with minimal toxicity. These early results highlight the potential of LRT to expand local control options in advanced STT. Prospective trials are warranted to define optimal dose, lattice design, biomarkers, and long-term safety. Keywords: Lattice RT, Sarcoma, Bulky tumors Hypofractionated preoperative radiotherapy in soft tissue sarcoma of the extremities and trunk: outcomes from a prospective phase II study Anastasia Stergioula 1,2 , Argyris Moutsatsos 1 , Nikolaos Memos 3 , Stefania Kokkali 4 , Theodoros Kormas 5 , Anastasios Kyriazoglou 6 , Georgios Agrogiannis 7 , Evaggelos Pantelis 1,8 1 Radiotherapy Department, Iatropolis Clinic, Athens, Greece. 2 Radiation Oncology Center, Iaso General Hospital, Athens, Greece. 3 2nd Department of Surgery, Digital Poster 860 Medical School, Aretaieion Hospital, National and Kapodistrian University of Athens, Athens, Greece. 4 Oncology Unit, Department of Internal Medicine,
surgery. Results:
Median age was 67 years (range, 48–88); 70% were male. Tumor sites were lower extremities in the majority of patients (80%); median size was 9.4 cm (range, 4.0–24.5). Histologies included myxoid liposarcoma (40%), undifferentiated pleomorphic sarcoma (30%), myxofibrosarcoma (20%), and malignant peripheral nerve sheath tumor/leiomyosarcoma (10%). FNCLCC grades were G1 20%, G2 30%, and G3 50%. The median interval between RT and surgery was 70 days (47–151). R0 resection was achieved in 80% of cases. A pathologic complete response (pCR) – defined as ≤ 5% viable cells – was achieved in 70% of cases. Major wound complications occurred in 2 patients (10%), none requiring reoperation. No acute grade ≥ 3 adverse event was observed. Late grade ≥ 3 events included fibrosis (20%) and hyperpigmentation (10%). After a
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