ESTRO 2022 - Abstract Book

S1031

Abstract book

ESTRO 2022

Our initial exploratory abstract reveals that inclusion of IMC for modulated radiation therapy has no substantial impact on heart dose, even though it comes with a heightened risk of under dosage on exclusion.

PO-1218 Ultra-hypofractionated whole breast radiotherapy as adyuvant treatment for early breast cancer

C. Camacho Fuentes 1 , A. Lanuza Carnicer 2 , C. Sánchez Cortés 1 , C. Escuin Troncho 2 , M. Calderó Torra 1 , M. Gascón Ferrer 1 , A.E. Pardo Sus 1 , S. Flamarique Andueza 2 , A. Campos Bonel 2 , M.P. Sanagustin Piedrafita 2 , R. Ibáñez Carreras 2 1 Lozano Blesa Clinical Universitary Hospital, Radiation Oncology, Zaragoza, Spain; 2 Miguel Servet Universitary Hospital, Radiation Oncology, Zaragoza, Spain Purpose or Objective Radiotherapy is an essential treatment in the local control of breast cancer. Standard treatment is currently carried out in 15 daily sessions. At present, following the results of the phase III Fast-Foward trial and in view of the situation triggered by COVID-19, the number of sessions has been reduced to 5. We present the data of our series to evaluate the results of the extreme hypofractionation scheme as a radiotherapy treatment for breast cancer at the Multihospital Clinical Unit of Radiation Oncology of Aragón (UCMORA). Materials and Methods After implantation, 115 patients were treated with 3D conformal radiotherapy between April 2020 and May 2021 at UCMORA using the extreme hypofractionation scheme (26 Gy at 5.2 Gy per fraction in 5 fractions). Demographic, tumor, dosimetric and toxicity characteristics were analyzed. Results The mean age was 63.5 years. 53 patients were treated at the Lozano Blesa Clinical Universitary Hospital and 62 at the Miguel Servet Universitary Hospital, in total 59 right and 56 left breasts. The predominant histology was infiltrating ductal carcinoma (84.3%), followed by infiltrating lobular carcinoma (10.4%), ductal carcinoma in situ (4.3%) and mucinous (0.9%). 51.7% were luminal A, 39.1% luminal B, 1.8% Her2 positive and 7.8% triple negative. In relation to staging, we found 4pTis, 8pT1a, 45pT1b, 58pT1c, 2Nx, 8N0, 1Nmi and 13N1a. Only 45% had acute toxicity at one month after the end of treatment, predominantly G1 radiodermatitis (86.6%), followed by G2 (11.2%) and G3 (2.2%). When analyzing the dose-volume histograms, values were obtained for ipsilateral lung V8 between 1.32 and 21.2%, for the heart, in case of left breast a median for V1.5 of 8.2% and 1.05% for V7; in case of right breast the median Dmed for the heart was 0.5Gy.

Conclusion Ultra-hypofractionated whole breast radiotherapy as a radiation treatment for breast cancer is well tolerated, reduces costs and number of sessions, while increasing comfort for patients.

PO-1219 Pattern of care for brain metastasis from breast cancer over the past 10 years in Korea

J.S. Kim 1 , K. Kim 2 , W. Jung 2 , K.H. Shin 1 , S. Im 3 , H. Kim 4 , Y.B. Kim 5 , J.S. Chang 5 , J.H. Kim 3,17 , D.H. Choi 6 , Y.H. Park 7 , D.Y. Kim 8 , T.H. Kim 8 , B.O. Choi 9 , S. Lee 9 , S. Kim 10 , J. Kwon 11 , K.M. Kang 12 , W. Chung 13 , K.S. Kim 14 , J.H. Nam 15 , W.S. Yoon 16 , J. Cha 18 , Y.K. Oh 19 , I.A. Kim 1 1 Seoul National University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of; 2 Ewha Womans University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of; 3 Seoul National University College of Medicine, Department of Internal Medicine, Seoul, Korea Republic of; 4 Chung-Ang University College of Medicine, Department of Internal Medicine, Seoul, Korea Republic of; 5 Yonsei University College of Medicine, Department of Internal Medicine, Seoul, Korea Republic of; 6 Sungkyunkwan University School of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of; 7 Sungkyunkwan University School of Medicine, Department of Internal Medicine, Seoul, Korea Republic of; 8 National Cancer Center, Proton Therapy Center, Goyang, Korea Republic of; 9 The Catholic University of Korea, Department of Radiation Oncology, Seoul, Korea Republic of; 10 Seoul Metropolitan Government Seoul National University Boramae Medical Center, Department of Radiation Oncology, Seoul, Korea Republic of; 11 Chungnam National University College of Medicine, Department of Radiation Oncology, Daejeon, Korea Republic of; 12 Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Department of Radiation Oncology, Changwon, Korea Republic of; 13 Chonnam National University Medical School, Department of