ESTRO 2020 Abstract book

S558 ESTRO 2020

support that the lung SBRT is a feasible and safe method for BCLM with excellent LC and acceptable toxicities. PO-0960 Metastatic breast cancer – Survival impact of locoregional treatment C.A.D.N. Laranja 1 , F. Sousa 1 , I. Rodrigues 1 , B. Castro 1 , I. Azevedo 1 , J. Conde 1 , V. Castro 1 , N. Stas 1 , H. Pereira 1 1 Instituto Português de Oncologia do Porto, Radioterapia externa, Porto, Portugal Purpose or Objective Purpose/Objective: Breast cancer is one of the most common cancers worldwide among women. Stage IV presentation at diagnosis involves only 3-8% of patients. The associated survival at this stage, may vary from months to years, however the prognosis is always reserved. The recommended therapeutic approaches rely mainly on systemic treatment, reserving locoregional treatment (LRT), namely radiotherapy (RT) and surgery, for palliative interventions related to the evolution of the disease. Some studies, however, have suggested a benefit of LRT of the primary tumor in clinical outcomes. The aim of this study, was to assess the impact of LRT on breast cancer patients presenting with stage IV at diagnosis in terms of OS and PFS. Material and Methods Material and methods: Retrospective analysis of 198 cases diagnosed with de novo stage IV breast cancer, treated at our institution between January 2013 and December 2017. Patients were divided in two groups those who underwent LRT of the primary tumor plus systemic therapy (LRT group) and those who only received systemic therapy (no- LRT group). Among those undergoing LRT, sub-groups where created: patients undergoing surgery, RT or surgery plus RT. Progression free survival (PFS) and overall survival (OS) were investigated. Statistical analysis was conducted using SPSS version 24. Results Results: The median age of the cohort was 53 years (30- 88). Of the 198 patients, 89 were included in no-LRT group and 111 included in LRT group. The median follow-up was 37 months. The 3-year OS for LRT group was 65.7% and for no-LRT group 46.5% (p=0.014), LRT/no-LRT hazard ratio (HZ) 0.52 [CI95% 0.34-0.80]. The 3-year PFS was 37.2% for LRT group and 15.1% for no-LRT group (p<0.01), ), LRT/no- LRT HZ 0.54 [CI95% 0.37-0.78]. On a multivariate analysis for metastatic locations TLR had better OS than the no- LRT for visceral metastases (mets) (p<0.01) and had a better PFS for bone mets (p<0.01) and visceral mets (p=0.01). The LRT group was further divided in subgroups: Surgery (38 patients), RT (4 patients) and RT+Surgery (69 patients). Because RT group was too small, we excluded it for the posterior analysis. The 3-year OS for Surgery was 62.9% and for RT+Surgery was 70% (p=0.14). The 3-year PFS was 19.8 for Surgery and 47.8% for RT+Surgery (p<0.01). Conclusion Conclusion: Loco-regional therapies, especially the association between surgery and radiation therapy, may have an important role to play in the treatment of selected patients with stage IV breast cancer, together with systemic therapies. Our study suggests LRT may improve OS and PFS in this population. Further investigation is important to understand, if interventions that prolong OS and PFS in stage IV breast cancer patients improve their health-related quality of life. PO-0961 Postoperative Single Fraction APBI: Tolerability, QOL and Cosmesis of a Novel Phase I/II Trial W. Kennedy 1 , M. Thomas 1 , J. Stanley 1 , L. Ochoa 1 , A. Price 1 , O. Green 1 , I. Zoberi 1 1 Washington University School of Medicine, Radiation Oncology, St. Louis, USA

Results The median follow-up was 60 months (4-78 months). A complete pathological response was achieved in 55.0% of patients. The published 2-year data were: overall survival (OS) 89%, disease free survival (DFS) 80% and local- recurrence-free survival (LRFS) 95%. The 5-year data changed to: OS 82%, DFS 77% and LRFS 91%. Among all patients who received implant-based IBR, 5 patients developed serious wound-healing problems with implant loss, 4 of them in the first 2 years after the IBR and one patient later on. The cosmetic results were excellent or good at 2-years in 66% of the patients treated with upfront mastectomy and 36% of the patients who had previously undergone BCS. After 5-years, cosmetic results remained similar, although 3 patients needed re-operations because of contractures (1 pat), implant implant rupture (1 patient) and lipofilling (1 pat). The most satisfactory results continued to be achieved with autologous-tissue reconstruction. Conclusion After mean follow-up of 5 years, the neoadjuvant chemo- /radiotherapy concept for LABC achieves very similar results as at 2-years-follow-up. Careful patient selection is mandatory to achieve a good oncological and cosmetic success using this treatment strategy. PO-0959 Treatment outcomes of breast cancer lung metastasis treated with stereotactic body radiotherapy O.C. Güler 1 , S.Y. Sari 2 , M. Gultekin 2 , B.A. Yıldırım 3 , O. Ozyılkan 4 , F. Yıldız 2 , C. Onal 3 1 Baskent Universitesi Tip Fakultesi- Adana Hastanes, Radiation Oncology, Adana, Turkey ; 2 Hacettepe University, Radiation Oncology, Ankara, Turkey ; 3 Baskent University, Radiation Oncology, Adana, Turkey ; 4 Baskent University, Medical Oncology, Adana, Turkey Purpose or Objective To analyze the outcomes of breast cancer lung metastasis (BCLM) treated with stereotactic body radiotherapy (SBRT) and systemic treatment. Material and Methods The treatment outcomes of 19 patients with oligometastasis (<5 metastases) at the time of lung metastasis (LM) or who became oligometastatic after systemic treatment were assessed. A total of 23 LM’s were treated with SBRT with a median 3 fractions (range, 3-10 fractions) to a total dose of 60 Gy (range, 30-60 Gy) between May 2011 and February 2019. The local control (LC), overall survival (OS), and progression-free survival (PFS) rates were calculated using Kaplan-Meier analyses. Results Median age and follow-up time were 47 years (range 32 – 76 years) and 14.5 months (range 1.1 – 49.9 months), respectively. Among 19 patients, 16 (84%) had solitary LM while 2 patients (11%) had two lesions and 1 patient (5%) had three lesions. Estrogen receptor (ER) and progesterone receptor (PR) were positive in 12 patients (52%) and 8 patients (35%), respectively. All patients had mastectomy for primary disease, and 17 patients (89%) received postoperative adjuvant chemotherapy and radiotherapy, while 2 patients (17%) had adjuvant chemotherapy only. Most of the patients [17 patients (89%)] developed LM during the follow-up of initial treatment, while only 2 patients (11%) had LM at the time of first diagnosis. At last visit, 11 patients (58%) had disease recurrence, median 8.4 months (range 3 – 16.3 months) after completion of liver SBRT. Only 5 patients (26%) had local recurrences. Median OS and PFS were 19.1 months [95% confidence interval (CI) 11.2 – 26.9 months]) and 8.3 months (95% CI; 7.9 – 8.8 months), respectively. The 1-year LC and OS rates were 49% and 82%, respectively. Conclusion This study is the first to evaluate the feasibility of SBRT to BCLM patients in a larger patient cohort. Our findings

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