ESTRO 2022 - Abstract Book

S1673

Abstract book

ESTRO 2022

Conclusion In this preliminary analysis deep-learning auto-segmentation seems to provide acceptable pelvic OARs delineations. For less accurate organs, AC could be considered a starting point for review and manual adjustment. Our results suggest that AC could become a useful time-saving tool to optimize workload and resources in RT departments. Further experiences with larger data numbers are needed to confirm its clinically viability are needed.

PO-1888 Dose received by axillary lymph notes in breast cancer adjuvant radiotherapy

N. Attia 1 , S. Tbessi 2 , A. Oualha 3 , F. Bouguerra 3 , B. Amri 3 , R. Hammouda 3 , O. Kallala 3 , R. Saidi 3 , S. Belajouza 3 , N. Bouzid 3 , S. Tebra 3 1 Farhat Hached Hospital , Radiotherapy, Sousse, Tunisia; 2 Farhat Hached Hospital, radiotherapy, Sousse, Tunisia; 3 Farhat Hached Hospital, Radiotherapy, Sousse, Tunisia Purpose or Objective The axillary region is considered problematic; as it is an organ at risk (OAR), a predictive dosimetric parameter of long term lymphedema, and a residual-disease site in case of breast cancer radiotherapy. The purpose of our study is to determine the dose received by the axillary area in adjuvant radiotherapy for breast cancer and to assess its clinical impact on long term lymphedema. Materials and Methods A retrospective dosimetric study was carried out in the Radiotherapy Department of Farhat Hached Hospital of Sousse. It included 50 female patients treated with three-dimensional adjuvant radiotherapy for breast cancer between 2018 and 2019. The axillary area was delineated according to the European Organization for Research and Treatment of Cancer (EORTC) guidelines. Results The average age was 52 [30-80]. Sixty-four percent of our patients had a mastectomy with ipsilateral axillary lymph node dissection (IALND), while 36% had a lumpectomy with a IALND. 17 patients among the 50 had lymph node metastasis (N+).Thirty-five patients (70%) received regional radiotherapy and 15 patients (30%) had only local radiotherapy with two tangential fields.All the patients were treated with normofractionated radiotherapy dose of 50Gy. Patients with conservative surgical treatment or with a T4 classified tumors, received additional boost up to 66Gy (21 patients) and up to 70Gy for tumoral surgical limits (1 patient). The mean axillary volume was 77.9 cm3 [9.4-181]. The average mean dose, the maximal dose and the minimal dosereceived by the axillary region were respectively 28.49Gy [3.19-53.7Gy], 54.18Gy [33.96-72.63Gy] and 2.61Gy [0.32-10.74].Late complications of lymphedema and radio induced dermatitis (GI and II according to the CTCAE V5.0 scale) were observed respectively in 6(12%)and 17(34%) patients. Conclusion Based on the results of our study, we have observed that the axillary area received unintentional yet significant doses during breast irradiation either by the tangential fields or by the additional supraclavicular field. Some authors consider