medwireNews: Stereotactic ablative body radiotherapy (SABR) offers similar outcomes, in terms of toxicity and efficacy, whether it is given as a single fraction or in multiple fractions to patients with up to three lung oligometastases, SAFRON II trial data show.
However, Shankar Siva (Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia) and colleagues say that the shorter duration of single-fraction SABR may mean that it is “preferred from resource and patient perspectives.”
The multicenter phase 2 trial included 90 participants (mean age 67 years, 64% men) with one to three lung oligometastases of 5 cm or smaller from any nonhematologic malignant tumors. They were randomly assigned to receive SABR to each oligometastasis (n=133 in total) in a single fraction of 28 Gy or in four fractions of 12 Gy.
Siva and team report that 5% of 38 evaluable patients in the single-fraction arm experienced the primary outcome of a grade 3 or worse treatment-related adverse event (AE) within a year. This did not significantly differ from the rate of 3% among the 38 evaluable patients in the multifraction arm.
Of note, the single grade 3 or worse AE observed in the multifraction arm was treatment-related hypoxia and radiation pneumonitis, which resulted in the death of the patient who had unrecognized underlying interstitial lung disease.
The researchers also report that, during a median 36.5 months of follow-up, there were no significant differences between the two treatment arms in the secondary outcomes of freedom from local failure, overall survival, disease-free survival, and the patient-reported outcomes of symptom severity and interference and health-related quality of life.
For example, at 1 year, the freedom from local failure rate was 93% in the single fraction arm and 95% in the multifraction arm, while rates at 3 years were 64% and 80%, respectively.
For overall survival, the estimated 1-year rates were 95% and 93% in the single fraction and multifraction arms, respectively, with 3-year rates a corresponding 81% and 67%.
The authors conclude in JAMA Oncology that “neither arm demonstrated evidence of superior safety, efficacy, or symptom burden; however, single-fraction SABR is more efficient to deliver.”
They add: “In the context of the COVID-19 global pandemic, single-fraction schedules may be particularly attractive because they may reduce potential transmission risk compared with more protracted schedules.”
In an accompanying comment, Arya Amini, from City of Hope National Medical Center in Duarte, California, USA, says the “SAFRON II study answers the fundamental question that up to this point was not directly answered, whether SABR in 1 to 3 fractions can safely be delivered to multiple pulmonary metastases.”
He adds that the study “paves the way for additional trials that are needed to identify the appropriate patients for aggressive local therapy, to ensure adverse events are limited, and to better understand the biological interaction of SABR with the tumor microenvironment and immune response.”
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