Stereotactic body frame based fractionated radiosurgery on consecutive days for primary or metastatic tumors in the lung

To evaluate the feasibility and treatment outcomes of stereotactic radiosurgery (SRS) using a stereotactic body frame (Precision Therapy™), we prospectively reviewed 34 tumors of the 28 patients with primary or metastatic intrathoracic lung tumors. Eligible patients included were nine with primary lung cancer and 19 with metastatic tumors from the lung, liver, and many other organs. A single dose of 10 Gy to the clinical target volume (CTV) was delivered to a total dose of 30–40 Gy with three to four fractions. Four to eight coplanar or non-coplanar static fields were generated to adequately cover the planning target volume (PTV) as well as to exclude the critical structures as much as possible. More than 90% of the PTV was delivered the prescribed dose in the majority of cases (average; 96%, range; 74–100%). The mean PTV was 41.4 cm³ ranging from 4.4 to 230 cm³. Set-up error was within 5 mm in all directions (X, Y, Z axis). The response was evaluated by using a chest CT and/or ¹⁸FDG-PET scans after SRS treatment, 11 patients (39%) showed complete response, 12 (43%) partial response (decrease of more than 50% of the tumor volume), and four patients showed minimally decreased tumor volume or stable disease, but one patient showed progression disease. With a median follow-up period of 18 months, a local disease progression free interval was ranging from 7 to 35 months. Although all patients developed grade one radiation pneumonitis within 3 months, none had symptomatic or serious late complications after completing SRS treatment. Given these observations, it is concluded that the stereotactic body frame based SRS is a safe and effective treatment modality for the local management of primary or metastatic lung tumors. However, the optimum total dose and fractionation schedule used should be determined after the longer follow-up of these results.