ESTRO 2022 - Abstract Book

S1007

Abstract book

ESTRO 2022

Pt, tumor and treatment characteristics were collected from the Electronic Patient Journal (EPJ) and the information system of Varian for pts treated in a VB. The time period of interest was the first six months of 2019 and 2021 representing the status before and after initiation of the DBCG Proton trial as of June 2020. Only pts with BC and indication for adjuvant RT were candidates. Since 2019, pts with bilateral BC have routinely been treated in a VB for correct application of the Varian Truebeam respiratory gating system. Results During 2019, five pts were treated in a VB, and they all had an IF due to restricted mobility of the arm. During 2021, 20 pts were treated in IF. Nine pts (45%) were treated in VB due to restricted mobility of the arm, seven (35%) due to bilateral BC and three patients (15%) had a VB in order to decrease the radiation dose to organs at risk (lungs and heart). For one patient the reason was not indicated. A lateral-decubitus position was used as a new technique in two cases to decrease the radiation dose to organs at risk. Conclusion Since initiation of the DBCG Proton trial, the photon clinic has individualized the photon RT by using more individualized treatment positioning and introducing the lateral-decubitus position. Furthermore, the level of accepting restricted arm mobility was lowered causing an increased number of pts with arm problems to be treated in a VB. It is likely that more patients may gain from using a VB and alternative treatment positions, and guidelines for identifying candidates for RT in a VB should be developed. 1 IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, Negrar, Italy; 2 Istituto Clinico Catanese, Unità operativa di Radioterapia Humanitas, Catania, Italy; 3 IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, N egrar, Italy; 4 IRCCS Sacro Cuore Don Calabria Hospital, Advanced Radiation Oncology Department, Catania, Italy Purpose or Objective breast cancer is a heterogenous disease with a deep tailoring level. Evidence are accumulating on the role of stereotactic body radiotherapy (SBRT) in the management of oligometastatic disease. While in other histology there is a large amount of data, the evidence in oligometastatic breast cancer is limited. The aim of the present study is to show the effectiveness of SBRT in delaying the switch to a subsequent systemic treatment line in oligoprogressive breast cancer patients. Materials and Methods retrospective analysis from two Institutions. The primary end-point was time to next systemic treatment (NEST). Secondary end-points were freedom from local progression (FLP), time to the polymetastatic conversion (tPMC) and overall survival (OS). Results One-hundred fifty-three (153) metastases in 79 oligoprogressive breast cancer patients were treated with SBRT. The median follow-up was 24 months. The median NEST was 8 months. Factors predictive of NEST at the multivariate analysis (MVA) was the number of treated oligometastases (HR 1.765, 95%CI 1.322-2.355; p=0.00). Systemic treatment after SBRT was changed in 29 patients for polymetastatic progression and in 10 patients for oligometastatic progression <6 months after SBRT. The 2-year FLP in the overall population was 86.7%. A biological effective dose (BED) >70Gy10 was associated with improved FLP (90% versus 74.2%). The median tPMC was 10 months. At the MVA the only factors significantly associated with tPMC were the number of oligometastases (HR 1.172, 95%CI 1.000-1.368; p=0.03), and the local control of the treated metastases (HR 2.726, CI95% 1.108-6.706; p=0.02). Conclusion SBRT can delay the switch to a subsequent systemic treatment, however patient’s selection is necessary. Several predictive factors for treatment tailoring were identified. PO-1188 Stereotactic body RT (SBRT) and concomitant systemic therapy in oligoprogressive breast cancer L. Nicosia 1 , V. Figlia 1 , N. Ricottone 2 , F. Cuccia 3 , R. Mazzola 1 , N. Giaj-Levra 1 , F. Ricchetti 1 , M. Rigo 1 , A. Girlando 4 , F. Alongi 1

PO-1189 Survival rates for breast cancer patients with brain metastasis treated with radiation

M. Simonsen 1 , B. Vrou Offersen 2 , A. Bonde Jensen 2

1 Aarhus University Hospital , Department of Oncology, Aarhus, Denmark; 2 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark Purpose or Objective Due to advancements in systemic treatment, the survival of breast cancer (BC) patients (pts) has improved, resulting in an increased incidence of brain metastases (BM). Treatment options for BM are limited and primarily consist of palliative surgery and/or radiotherapy (RT) Our aim is to analyze survival time for BC pts treated with RT either alone or in combination with surgery, after first event of BM. Secondly, to evaluate prognostic impact of predefined factors.

Materials and Methods