Chmura S, Winter KA, Robinson C, et al. - Given the hypothesis that stereotactic body radiotherapy (SBRT) for oligometastases results in improved survival, and in view of little evidence supporting its safe use to treat patients with multiple metastases, researchers undertook this National Cancer Institute–sponsored phase 1 trial to establish safety of SBRT dose schedules in patients having 3 to 4 metastases or 2 metastases in close proximity to each other. This analysis involved metastases to 7 anatomic sites: bone/osseous (BO), spinal/paraspinal (SP), peripheral lung (PL), central lung (CL), abdominal-pelvic (AP), mediastinal/cervical lymph node (MC), and liver (L). A total of 35 patients experiencing oligometastatic breast, prostate, or non–small cell lung cancer were managed with ablative radiation. The starting dose was 50 Gy in 5 fractions (CL, MC), 45 Gy in 3 fractions (PL, AP, L), and 30 Gy in 3 fractions (BO, SP). Safety of standard doses was evident in all 35 evaluable cases, with a median of 3 metastases; no protocol-defined dose-limiting toxicities occurred, and more than 50% of patients were found alive at 2 years. Overall, SBRT was found safe to treat patients with 3 to 4 metastases or 2 metastases in close proximity. No treatment-related deaths occurred. Late grade 3 adverse events show the requirement for extended follow-up among long-surviving patients with oligometastatic disease.