Since 1998, we have treated primary and oligometastatic lung tumors with stereotactic body radiotherapy (SBRT). The term "oligometastasis" is used to indicate a small number of metastases limited to an organ. We evaluated our clinical experience of SBRT for oligometastatic lung tumors.

A total of 34 patients with oligometastatic lung tumors were included in this study. The primary involved organs were the lung (n = 15), colorectum (n = 9), head and neck (n = 5), kidney (n = 3), breast (n = 1), and bone (n = 1). Five to seven, noncoplanar, static 6-MV photon beams were used to deliver 48 Gy (n = 18) or 60 Gy (n = 16) at the isocenter, with 12 Gy/fraction within 4-18 days (median, 12 days).

The overall survival rate, local relapse-free rate, and progression-free rate at 2 years was 84.3%, 90.0%, and 34.8%, respectively. No local progression was observed in tumors irradiated with 60 Gy. SBRT-related pulmonary toxicities were observed in 4 (12%) Grade 2 cases and 1 (3%) Grade 3 case. Patients with a longer disease-free interval had a greater overall survival rate.

The clinical result of SBRT for oligometastatic lung tumors in our institute was comparable to that after surgical metastasectomy; thus, SBRT could be an effective treatment of pulmonary oligometastases.