Clinical outcomes of stereotactic ablative radiotherapy in patients with pulmonary metastasis.

BACKGROUNDS: In addition to its curative use for early stage lung cancer, stereotactic ablative radiotherapy is also indicated for pulmonary metastatic disease. Aims of this study were to retrospectively analyze treatment outcomes and to find prognostic factors for survivals. METHODS: Treatment outcomes and toxicities of 85 cases of SABR in 72 patients were retrospectively reviewed from September 2012 to April 2015. Prognostic factors were analyzed using Cox proportional hazards regression. RESULTS: The local failure-free survival rate at 2 years was 98%. Of the case, 1-year and 2-year progression-free survival rates were 62% and 48%, and overall survival rates were 90% and 72%, respectively. Multivariate analyses demonstrated that controlled primary cancer (P = 0.01), absence of extra-pulmonary metastatic disease (P < 0.01) and disease-free interval longer than 1 year (P < 0.01) favorably affected progression-free survival. Furthermore, the absence of extra-pulmonary metastatic disease (P < 0.01) increased overall survival as well. Grade 1 or 2 radiation pneumonitis was found in 37 cases, and Grade 1 chest wall pain was found in 1 case. CONCLUSIONS: Stereotactic ablative radiotherapy demonstrated good local control with tolerable adverse effects for pulmonary metastasis. The presence or absence of extra-pulmonary metastasis was found to be prognostic factor of mortality after stereotactic ablative radiotherapy treatment.