Stereotactic Body Radiation Therapy for Extracranial Oligometastatic Non-small-cell Lung Cancer: A Systematic Review

Stereotactic body radiation therapy (SBRT) has emerged as a treatment modality for selected patients with oligometastatic non-small-cell lung cancer (NSCLC). The objectives of this systematic review were to explore the benefits and risks of SBRT for extracranial oligometastatic NSCLC. The MEDLINE, Embase, PubMed, and CENTRAL databases were searched for relevant articles from January 1, 2000 to July 23, 2019. Fully published phase III or phase II trials of any sample size were included. Retrospective series published in manuscript form with at least 50 patients were also included. Four prospective phase II randomized trials (total, 188 participants), 4 prospective non-randomized studies (total, 140 participants), and eleven retrospective studies (total, 1288 participants) were included in this systematic review. A variety of dose fractionation schemes were used. The median overall survival (OS) ranged from 13.5 to 55 months. Progression-free survival (PFS) ranged from 4.4 to 14.7 months. Quality of life outcomes were reported in 2 studies. None of the studies reported symptom control outcomes. There are no fully completed phase III randomized trials that clarify the risks and benefits of SBRT for oligometastatic NSCLC. Higher PFS and OS with SBRT were reported in 4 phase II randomized studies. The results from mature phase III randomized data regarding whether SBRT for oligometastatic NSCLC benefits patients in terms of OS, PFS, quality of life, and symptom control are needed.