ESTRO 2023 - Abstract Book

S494

Sunday 14 May 2023

ESTRO 2023

Conclusion After central SABR, the rates of high grade clinical toxicity and bronchial obstruction/atelectasis almost doubled to 40% in patients surviving more than three years. This highlights the importance of identifying better planning constraints for central airways, and for improved SABR delivery approaches for central tumors. OC-0610 Long-term outcomes of TROG13.01 SAFRON II: Single vs multi-fraction SABR for oligometastases to lung S. Siva 1 , P. Sakyanun 2 , T. Mai 3 , W. Wong 4 , A. Lim 5 , J. Ludbrook 6 , C. Bettington 7 , A. Rezo 8 , D. Pryor 3 , N. Hardcastle 9 , T. Kron 9 , B. Higgs 10 , H. Le 10 , M. Skala 11 , S. Gill 12 , R. Awad 11 , G. Sasso 13 , S. Vinod 14 , R. Montgomery 15 , D. Ball 1 , M. Bressel 16 1 Peter MacCallum Cancer Centre, Department of Radiation Oncology, Melbourne, Australia; 2 Phramongkutklao Hospital, Department of Radiation Oncology, Bangkok, Thailand; 3 Princess Alexandra Hospital, Radiation Oncology Centre, Brisbane, Australia; 4 Prince of Wales Hospital, Department of Radiation Oncology, Sydney, Australia; 5 Austin Health, Department of Radiation Oncology, Melbourne, Australia; 6 Calvary Mater Newcastle, Department of Radiation Oncology, Newcastle, Australia; 7 Royal Brisbane and Women's Hospital, Department of Radiation Oncology, Brisbane, Australia; 8 Canberra Hospital, Radiation Oncology Department, Canberra, Australia; 9 Peter MacCallum Cancer Centre, Department of Physical Sciences, Melbourne, Australia; 10 Royal Adelaide Hospital, Department of Radiation Oncology, Adelaide, Australia; 11 Royal Hobart Hospital, Radiation Oncology, Hobart, Australia; 12 Sir Charles Gairdner Hospital , Department of Radiation Oncology, Perth, Australia; 13 Auckland City Hospital , Radiation Oncology Department, Auckland, New Zealand; 14 Liverpool Hospital, Cancer Therapy Centre, Sydney, Australia; 15 TROG Cancer Research, Research Development, Newcastle, Australia; 16 Peter MacCallum Cancer Centre, Centre for Biostatistics and Clinical Trials, Melbourne, Australia Purpose or Objective There is a lack of randomized evidence to guide the optimal approach for SABR in patients with pulmonary oligometastases. We conducted a randomized trial comparing single with multi-fraction SABR for patients with 1-3 pulmonary oligometastases. Herein, we report the extended follow-up survival outcomes of the Trans Tasman Radiation Oncology Group (TROG) 13.01 SAFRON II study. Materials and Methods TROG 13.01 SAFRON II was a multicentre unblinded randomized phase II trial across 13 centres in Australia and New Zealand. Enrolment was between 2015 and 2018, with minimum follow-up of 2 years. Extended follow-up was until Sep 2022. Participants had 1–3 oligometastases of <5cm diameter to the lung from any non-haematological malignancy, located away from central airways, ECOG 0-1, and all primary and extrathoracic disease controlled with local therapy. The interventions were either a single fraction of 28Gy (SF Arm) or four fractions of 12Gy (MF Arm) prescribed to the periphery (D99 ≥ 100%) of each oligometastasis. Participants were stratified by the number of metastases and histology (colorectal versus non colorectal). Participants were not allowed systemic therapy during or after receipt of SABR until the time of progression. The primary outcome was grade 3 treatment related AEs (CTCAE v4.0) occurring within 1 year of SABR. Secondary survival outcomes included disease free survival (DFS) and overall survival (OS) were reported. Results 90 participants were randomized, with n = 87 treated for 133 pulmonary oligometastases (Figure 1). Median follow-up was 5.4 years. Median age was 68 years, 64% were male. The number of pulmonary oligometastases was 1 in 51 (59%), was 2 in