ESTRO 2021 Abstract Book

S1172

ESTRO 2021

Conclusion Based on data from our experience, lack of 22q12 translocation showed a correlation with DMFS and OS in non- metastatic EWS . Giving its potentially prognostic role, assessment of 22q11 rearrangement could be useful for treatment personalization. However, further prospective studies are needed to confirm these results. PO-1427 Clinical outcomes of scalp angiosarcoma treated with intensity-modulated radiotherapy T. Iwai 1 , S. Okabayashi 1 , R. Ashida 1 , T. Mitsuyoshi 1 , T. Imagumbai 1 , M. Kokubo 1 1 Kobe City Medical Center General Hospital, Radiation Oncology, Kobe, Japan Purpose or Objective Scalp angiosarcoma is rare cutaneous malignancy, which prognosis is very poor. Combined therapy including whole scalp radiotherapy (RT) is the treatment for scalp angiosarcoma and intensity-modulated radiotherapy (IMRT) is considered to have benefit for target coverage, however the clinical data is limited. We reviewed the patients with scalp angiosarcoma treated with IMRT in our institution. Materials and Methods Between November 2017 and December 2019, patients with scalp angiosarcoma without distant metastasis treated with IMRT in our hospital were evaluated. Both definitive RT and postoperative RT were included. Information regarding patient status, tumor characteristics, treatment characteristics and outcomes were obtained from the clinical records. Overall survival (OS) and progression-free survival (PFS) were calculated by the Kaplan-Meier method from the start date of surgery or definitive RT. Toxicity was evaluated by CTCAE version 4.0. Results Five patients were included in this study (Table 1). One patient had tumor invasion to salivary gland and regional lymph node metastasis at diagnosis. Definitive RT was performed for 2 patients and postoperative RT was performed for 3 patients. Surgical excision was performed with 1-3.5 cm margin. For RT, volumetric modulated arc therapy (VMAT) with 4 MV or 6 MV photon was used for all patients. The clinical target volume (CTV) was whole scalp for 4 patients, temporal scalp plus salivary gland for 1 patient, and both included 3-5 cm margin from tumor or surgical edge. The planning target volume (PTV) was CTV with a margin of 5 mm in all directions. All patients were treated with concurrent chemoradiotherapy with weekly paclitaxel (PTX) and 3 patients were treated with maintenance weekly PTX after RT. The median follow-up time was 25.6 months and 4 patients were alive with no evidence of disease. The one-year OS and PFS rates were both 80%. One patient exhibited recurrences in regional lymph node and salivary gland at 5.4 months after surgery. This patient exhibited also lung metastasis after first recurrences, which was cause of death, the recurrence from scalp was not observed. For acute and late toxicity, grade 3 dermatitis and grade 3 skin ulceration were observed for 2 patients, respectively. Any other grade 3 or higher acute and late toxicities were not observed.