Phase III Multi-Center, Prospective, Randomized Trial Comparing Single Dose 24 Gy Radiotherapy to a 3-Fraction SBRT Regimen in the Treatment of Oligometastatic Cancer.

Abstract

PURPOSE\nThis prospective phase III randomized trial was designed to test whether ultra-high single-dose radiotherapy (24 Gy SDRT) improves local control of oligometastatic lesions over a standard hypofractionated stereotactic body radiotherapy regimen (3 x 9 Gy SBRT). The secondary endpoint was to assess the associated toxicity and the impact of ablation on clinical patterns of metastatic progression.\n\n\nMETHODS AND MATERIALS\nBetween November 2010 and September 2015, 117 patients with 154 oligometastatic lesions (≤ 5/patient) were randomized in a 1:1 ratio to receive 24 Gy SDRT or 3 x 9 Gy SBRT. Local control within the irradiated field and the state of metastatic spread were assessed by periodic whole-body PET/CT and/or MRI imaging. Median follow-up was 52 months.\n\n\nRESULTS\n59 patients with 77 lesions were randomized to 24 Gy SDRT and 58 patients with 77 lesions to 3 x 9 Gy SBRT. The cumulative incidence of local recurrence for SDRT lesions was 2.7% (95% CI 0-6.5%) and 5.8% (95% CI 0.2-11.5%) at years two and three, respectively, compared to 9.1% (95% CI 2.6-15.6%) and 22% (95% CI 11.9-32.1%) for SBRT lesions (P=.0048). The two- and three-years cumulative incidence of distant metastatic progression in the SDRT patients were 5.3% (95% CI 0-11.1%), compared to 10.7% (95% CI 2.5-18.8%) and 22.5% (95% CI 11.1-33.9%), respectively, for the SBRT patients (P=.010). No differences in toxicity were observed.\n\n\nCONCLUSIONS\nThe study confirms SDRT as a superior ablative treatment, indicating that effective ablation of oligometastatic lesions is associated with significant mitigation of distant metastatic progression.