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