Safety, Efficacy, and Patterns of Failure After Single-Fraction Stereotactic Body Radiation Therapy (SBRT) for Oligometastases

PURPOSE: Fewer attendances for radiation therapy results in increased efficiency and less foot traffic within a radiation therapy department. We investigated outcomes after single-fraction (SF) stereotactic body radiation therapy (SBRT) in patients with oligometastatic disease. METHODS AND MATERIALS: Between February 2010 and June 2019, patients who received SF SBRT to 1 to 5 sites of oligometastatic disease were included in this retrospective study. The primary objective was to describe patterns of first failure after SBRT. Secondary objectives included overall survival (OS), progression-free survival (PFS), high-grade treatment-related toxicity (Common Terminology Criteria for Adverse Events grade ≥3), and freedom from systemic therapy (FFST). RESULTS: In total, 371 patients with 494 extracranial oligometastases received SF SBRT ranging from 16 Gy to 28 Gy. The most common primary malignancies were prostate (n = 107), lung (n = 63), kidney (n = 52), gastrointestinal (n = 51), and breast cancers (n = 42). The median follow-up was 3.1 years. The 1-, 3-, and 5-year OS was 93%, 69%, and 55%, respectively; PFS was 48%, 19%, and 14%, respectively; and FFST was 70%, 43%, and 35%, respectively. Twelve patients (3%) developed grade 3 to 4 treatment-related toxicity, with no grade 5 toxicity. As the first site of failure, the cumulative incidence of local failure (irrespective of other failures) at 1, 3 and 5 years was 4%, 8%, and 8%, respectively; locoregional relapse at the primary was 10%, 18%, and 18%, respectively; and distant failure was 45%, 66%, and 70%, respectively. CONCLUSIONS: SF SBRT is safe and effective, and a significant proportion of patients remain FFST for several years after therapy. This approach could be considered in resource-constrained or bundled-payment environments. Locoregional failure of the primary site is the second most common pattern of failure, suggesting a role for optimization of primary control during metastasis-directed therapy

Single-Fraction vs Multifraction Stereotactic Ablative Body Radiotherapy for Pulmonary Oligometastases (SAFRON II)

ImportanceEvidence is lacking from randomized clinical trials to guide the optimal approach for stereotactic ablative body radiotherapy (SABR) in patients with pulmonary oligometastases.ObjectiveTo assess whether single-fraction or multifraction SABR is more effective for the treatment of patients with pulmonary oligometastases.Design, setting, and participantsThis multicenter, unblinded, phase 2 randomized clinical trial of 90 patients across 13 centers in Australia and New Zealand enrolled patients with 1 to 3 lung oligometastases less than or equal to 5 cm from any nonhematologic malignant tumors located away from the central airways, Eastern Cooperative Oncology Group performance status 0 or 1, and all primary and extrathoracic disease controlled with local therapy. Enrollment was from January 1, 2015, to December 31, 2018, with a minimum patient follow-up of 2 years.InterventionsSingle fraction of 28 Gy (single-fraction arm) or 4 fractions of 12 Gy (multifraction arm) to each oligometastasis.Main outcomes and measuresThe main outcome was grade 3 or higher treatment-related adverse events (AEs) occurring within 1 year of SABR. Secondary outcomes were freedom from local failure, overall survival, disease-free survival, and patient-reported outcomes (MD Anderson Symptom Inventory-Lung Cancer and EuroQol 5-dimension visual analog scale).ResultsNinety participants were randomized, of whom 87 were treated for 133 pulmonary oligometastases. The mean (SD) age was 66.6 [11.6] years; 58 (64%) were male. Median follow-up was 36.5 months (interquartile range, 24.8-43.9 months). The numbers of grade 3 or higher AEs related to treatment at 1 year were 2 (5%; 80% CI, 1%-13%) in the single-fraction arm and 1 (3%; 80% CI, 0%-10%) in the multifraction arm, with no significant difference observed between arms. One grade 5 AE occurred in the multifraction arm. No significant differences were found between the multifraction arm and single-fraction arm for freedom from local failure (hazard ratio [HR], 0.5; 95% CI, 0.2-1.3; P = .13), overall survival (HR, 1.5; 95% CI, 0.6-3.7; P = .44), or disease-free survival (HR, 1.0; 95% CI, 0.6-1.6; P > .99). There were no significant differences observed in patient-reported outcomes.Conclusions and relevanceIn this randomized clinical trial, neither arm demonstrated evidence of superior safety, efficacy, or symptom burden; however, single-fraction SABR is more efficient to deliver. Therefore, single-fraction SABR, as assessed by the most acceptable outcome profile from all end points, could be chosen to escalate to future studies.Trial registrationClinicalTrials.gov Identifier: NCT01965223