Stereotactic body radiation therapy favors long-term overall survival in patients with lung metastases: five-year experience of a single-institution.

Background: Metastatic lung cancer is one of the most common oncologic problems. This study aimed to evaluate the long-term clinical outcome of stereotactic body radiation therapy (SBRT) for metastatic lung tumors.

Methods: We retrospectively reviewed the 71 patients with lung metastases, who had 172 lesions treated with SBRT from January 2000 to December 2006. All patients were unfit or failed after surgery and/or chemotherapy. The median total dose was 48 Gy (range, 30 - 60) in 4 (range, 2 - 12) fractions. The median size of the irradiated lesions was 2.1 cm (range, 0.9 - 7.9 cm).

Results: All but two patients received follow up. The median follow-up time was 24.7 months (range, 2.9 - 114.4 months). The median follow-up time for living patients was 86.8 months (range, 58.1 - 114.4 months). The 1-, 3-, 5-year local control and overall survival rates were 88.8%, 75.4%, 75.4% and 78.9%, 40.8%, 25.2%. Multivariate analysis showed that the absence of extrapulmonary metastases (P = 0.024; hazard ratio (HR), 1.894; 95% confidence interval (CI), 1.086 - 3.303) and disease-free interval ≤ 12 months (P = 0.014; HR, 0.511; 95%CI, 0.299 - 0.873) were independent prognostic factors. No grade 3 or more acute and late toxicities occurred. Only one patient developed a non-symptomatic rib fracture.

Conclusion: SBRT could be an alternative treatment to surgery for subsets of patients with lung metastases with favorable long-term survival and tolerable complications.