ESTRO 2020 Abstract Book

S346 ESTRO 2020

12 the Royal Marsden Hospital Nhs Foundation Trust, Radiotherapy, Sutton, United Kingdom ; 13 manchester University Nhs Foundation Trust, The Nightingale Centre, Manchester, United Kingdom ; 14 independent Cancer Patients' Voice, Icpv, London, United Kingdom ; 15 mount Vernon Cancer Centre, National Radiotherapy Trials Quality Assurance Group, Northwood, United Kingdom ; 16 guy's And St Thomas' Nhs Foundation Trust, Guy's Cancer Centre, London, United Kingdom ; 17 the Institute Of Cancer Research And Royal Marsden Hospital Nhs Foundation Trust, Radiotherapy And Imaging, Sutton, United Kingdom ; 18 clatterbridge Cancer Centre Nhs Foundation Trust, Radiotherapy, Liverpool, United Kingdom ; 19 the Institute Of Cancer Research And Royal Marsden Hospital Nhs Foundation Trust, Radiotherapy, Sutton, United Kingdom Purpose or Objective FAST-Forward aims to identify a 5-fraction schedule of adjuvant radiotherapy delivered in 1 week that is at least as effective and safe as the standard 15-fraction regimen after primary surgery for early breast cancer. Results of the 5-year primary analysis are presented. Material and Methods The FAST-Forward trial (ISRCTN19906132) randomised patients with invasive carcinoma of the breast (pT1-3 pN0- 1 M0) following breast conservation surgery (BCS) or mastectomy (immediate reconstruction allowed) to 40Gy in 15 fractions over 3 weeks (control), 27Gy or 26Gy in 5 fractions over 1 week (1:1:1) to whole breast/chest wall. Centres pre-specified tumour bed boost, if required, of 16Gy in 8 fractions or 10Gy in 5 fractions. Primary endpoint is local tumour control (absence of ipsilateral local tumour). Assuming a 2% 5-year event rate for 40Gy, non- inferiority is defined as ≤1.6% absolute excess for test schedules versus 40Gy, with critical hazard ratio (HR) of 1.81. Normal tissue effects (NTE) were assessed by clinicians (annually), by patients (6, 12, 24, 60m) and from photographs (24, 60m). Survival analysis methods assessed time to local tumour event, and longitudinal models for clinician-assessed NTE. Results From November 2011-June 2014 4096 consenting patients were recruited (1361 40Gy, 1367 27Gy, 1368 26Gy). Mean age was 61 years, 94% received BCS, 71% were grade 1 or 2, 81% were pathological node negative, 25% received adjuvant chemotherapy and 25% received a tumour bed boost. At a median follow-up of 71 months, 74 local tumour events have occurred (29 in 40Gy, 26 in 27Gy, 19 in 26Gy). HRs for local tumour event versus 40Gy were 27Gy: 0.88 (95%CI 0.52-1.50) and 26Gy: 0.64 (0.36-1.15). Non- inferiority was shown for each test group versus 40Gy. With a 5-year local tumour event rate in 40Gy of 2.0% (1.4-3.0), the estimated absolute differences vs 40Gy (and test against critical HR>1.81) were -0.2% (-1.0 - 1.0) for 27Gy (p=0.004) and -0.7% (-1.3 - 0.3) for 26Gy (p<0.001). Levels of marked NTE at 5 years were very low in all groups (44/3011 with available data; 1.5% overall). 5-year prevalence of any clinician-assessed moderate/marked breast NTE were 40Gy: 98/986 (9.9%), 27Gy: 155/1005 (15.4%), 26Gy: 121/1020 (11.9%). Including annual assessments from 1-5 years, ORs (95%CI) for any moderate/marked breast NTE versus 40Gy were 1.55 (1.32-1.84, p<0.001) for 27Gy and 1.12 (0.94-1.34, p=0.20) for 26Gy. Conclusion At 5 years, local tumour control after 5-fraction adjuvant breast radiotherapy was shown to be non-inferior to the standard 15-fraction schedule according to our pre-

Conclusion In this randomized phase II trial, dose escalation to the primary tumor as a whole or 50%SUV max in NSCLC patients led to respectively 97% and 91% FFLF at 1 year in central CT review. Many scans were not evaluable (27%), likely due to the effect of high dose radiation. Predefined FFLF increase from 70% to 85% was achieved in both arms, however the trial did not reach predefined sample size. In locally advanced non-resectable NSCLC a homogeneous boost, sparing central structures as much as possible, should be considered in future research. OC-0610 FAST-Forward phase 3 RCT of 1-week hypofractionated breast radiotherapy: 5-year results A.M. Brunt 1 , J.S. Haviland 2 , D.A. Wheatley 3 , M.A. Sydenham 2 , A. Alhasso 4 , D. Bloomfield 5 , C. Chan 6 , M. Churn 7 , S. Cleator 8 , C.E. Coles 9 , M. Emson 2 , A. Goodman 10 , A. Harnett 11 , P. Hopwood 2 , A.M. Kirby 12 , C. Kirwan 13 , C. Morris 14 , Z. Nabi 15 , E. Sawyer 16 , N. Somaiah 17 , L. Stones 2 , I. Syndikus 18 , M. Wilcox 14 , J.M. Bliss 2 , J.R. Yarnold 19 1 university Hospitals Of North Midlands And Keele University, Cancer Clinical Trials Unit- Cancer Centre- Royal Stoke Hospital, Nr. Crewe, United Kingdom ; 2 the Institute Of Cancer Research, Icr-Ctsu, Sutton, United Kingdom ; 3 royal Cornwall Hospital Nhs Trust, Oncology, Truro, United Kingdom ; 4 the Beatson West Of Scotland Cancer Centre, Beatson Oncology Centre, Glasgow, United Kingdom ; 5 royal Sussex County Hospital, Sussex Cancer Centre, Brighton, United Kingdom ; 6 nuffield Health Cheltenham Hospital, Breast Surgery, Cheltenham, United Kingdom ; 7 worcestershire Royal Hospital, Worcestershire Cancer Centre, Worcester, United Kingdom ; 8 imperial College Healthcare Nhs Trust, Radiotherapy, London, United Kingdom ; 9 university Of Cambridge, Department Of Oncology, Cambridge, United Kingdom ; 10 royal Devon And Exeter Hospital Nhs Foundation Trust, Exeter Oncology Centre, Exeter, United Kingdom ; 11 norfolk And Norwich University Hospitals Nhs Trust, Oncology, Norwich, United Kingdom;