Preliminary Results of Stereotactic Body Frame Based Fractionated Radiosurgery on Consecutive Days for Primary Lung Cancer or Metastatic Lung Tumors

ABSTRACT

To evaluate the feasibility and treatment outcomes of stereotactic radiosurgery (SRS) using a stereotactic body frame (Precision TherapyTM), we prospectively reviewed 34 tumors of the 28 patients with primary or metastatic intrathoracic lung tumors. Eligible patients included were 9 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 3~4 fractions. Four to 8 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 cc ranging from 4.4 to 230 cc. 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 4 patients showed minimally decreased tumor volume or stable disease, but 1 patient showed progressive disease. With a median follow-up period of 18 months, a median local disease progression free interval was 18 months ranging from 7 to 35 months. Although all patients developed grade 1 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.