ESTRO 2020 Abstract book

S571 ESTRO 2020

after CCCR. More than half of the patients were proposed to radical mastectomy (N=15, 64%) and 2 to palliative mastectomy. Subsequently, 8 patients (29%) had locoregional progression, 3 of them together with systemic progression; 19 (68%) patients had distant progression, mainly by hepatic, bone, cutaneous and nodal metastasis. With a median follow-up of 61 months, the OS was 12.7 months (CI 95% 4.6-20.7) and PFS was 4.6 months (CI 95% 2.5-6.6). Conclusion The use of a CCCR scheme for locally advanced disease after primary chemotherapy was associated with satisfactory response rates, with reversal of inoperability in a significant proportion of patients whilst maintaining acceptable toxicity. Prospective randomized studies are needed to validate this treatment. PO-0988 Is there a learning curve for SABR that affects overall survival outcomes in early stage NSCLC? C. Peedell 1 , E. Aynsley 1 , A. Wood 1 , G. Kumar 1 , S. Masinghe 1 , J. Reynolds 1 , C. Huntley 1 , A. Blower 1 , J. Green 1 , J. Bradley 1 , J. Veeratterapillay 1 , A. Hassani 1 , M. Anderson 1 , A. Greenhalgh 1 , J. Daniel 1 , A. Swingler 1 , M. Turnbull 1 , K. Burke 1 1 South Tees Hospitals NHS Foundation Trust, Oncology and Radiotherapy, Near Bedale, United Kingdom Purpose or Objective SABR has become the standard of care for medically inoperable, peripherally located, early stage NSCLC, but the question of whether the excellent long term outcomes published by pioneering academic institutions can be replicated in the “real-world setting” remains a pertinent one. As increasing numbers of institutions set up SABR programmes, it is important to understand whether learning curves that affect patient outcomes exist. Our cancer centre is a non-academic centre located in one of the most socially deprived regions in the UK, serving a population of 1.1million. Our SABR program for NSCLC started in 2009 and we present the long term outcomes of 418 patients treated by 5 different consultants of varying experience. Material and Methods Retrospective data was collected from consecutive patients with medically inoperable early stage (T1a-3 N0) NSCLC treated with SABR between Sept 2009 and May 2019. Patients with previous malignancy within 5yrs, or more than one primary lesion were excluded. Patients without a histological diagnosis required a PET+ve, growing lesion for inclusion. All patients were immobilised using the BodyFix system. The following risk- adapted dose/fractionation schedules were used: 54Gy/3#; 55Gy/5#; 60Gy/8#; 50Gy/10#. Overall Survival was assessed using the Kaplan-Meier method. Five different consultant clinical oncologists (A,B,C,D,E) treated patients during this period and individual consultant outcomes were assessed. OS of the first 25 patients treated versus all subsequent patients was calculated for 3 of the consultant cohorts (A,C,E) Results Poster: Clinical track: Lung

radiotherapy,. At 3 months, none of the patients had acute toxicity or breast related pain, only one patient had persistent tumour bleed and one patient had a residual fungating tumour. Clinical examination done at 3 months showed that 10 (55.5%) patients had partial response (PR), 6 (33.3%) patients had complete response (CR) and 2 (11.1%) patients had clinical progression. Radiological response assessment revealed that 10 (55.5%) patients had partial metabolic response(PMR), 4 (22.2%) patients had complete metabolic response(CMR), 1 (5.5%) patient had stable metabolic disease(SMD) and 3 (16.6%) patients had progressive metabolic disease. Of the three patients who had progressed, 1 patient progressed in the internal mammary nodal region. Conclusion Hypofractionated radiotherapy using this 1 week schedule showed acceptable toxicity, satisfactory local control and excellent palliation in patients with advanced incurable breast cancer. PO-0986 Concurrent Chemoradiation for Inoperable Locally Advanced Breast Cancer after Primary Chemotherapy B. Castro 1 , I. Rodrigues 1 , I. Azevedo 1 , J. Savva-Bordalo 2 , D. Moreira 1 , H. Pereira 1 1 Instituto Português de Oncologia do Porto, Serviço de Radioterapia Externa, Porto, Portugal ; 2 Instituto Português de Oncologia do Porto, Serviço de Oncologia Médica, Porto, Portugal Purpose or Objective Locally Advanced Breast Cancer (LABC) entitles a heterogeneous group of tumors with poor prognosis for whom initial systemic treatment is proposed to downsize the tumor. Concurrent chemoradiation (CCCR) schemes, based on the radiosensitizing properties of anti-neoplasm drugs, are largely used as a radical option for inoperable tumors, such as those of the head and neck and digestive tract, with increased rates of local control. The use of CCCR in the LABC has been hypothesized for both palliation and locoregional control. The primary objective of this study was to evaluate the efficacy of CCCR through response rates and survival analysis; the secondary objective was to report the associated toxicity. Material and Methods Data from patients with LABC (stage III/IV) submitted to CCCR in a cancer center between January 2009 and December 2018 were retrospectively reviewed. Descriptive analysis was used to characterize population and clinical-pathological variables. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan-Meier method. The response and toxicity (CTCAE 5.0) rates were also evaluated. Results Twenty-eight female patients were included, with median age at diagnosis of 52 years (32-79) and PS ≤2. The majority of patients (N=25, 89%) were treated for ductal carcinoma, mostly grade 3 (N=17, 61%), 8 (29%) Her2 positive and 9 (32%) triple-negative tumors. The majority presented at stage IV (N=15, 54%). All patients were submitted to CCCR due to inoperable disease after primary chemotherapy. Weekly taxotere 25- 35mg/m 2 was used as radiosensitizer (3 to 8 cycles). Radiotherapy was prescribed to 50Gy in 25 daily fractions in a median overall treatment time of 34 days (33-62). In the majority of patients (N=23, 32%), regional nodes were irradiated in addition to the breast. Regarding toxicity, were reported 19 (68%) cases of radiodermatitis, 4 of which were grade 3; 7 (25%) cases of mucositis grade ≤2; and 3 (11%) cases of hematological toxicity grade 3. One patient did not complete CCCR because of non-related death. The majority of patients (N=18, 64%) achieved partial response, 3 (11%) had complete clinical response and 2 (7%) had stable disease; only 4 (14%) patients progressed