Stereotactic body radiotherapy (sbrt) in lung oligometastatic patients: role of local treatments

Background: Data in the literature suggest the existence of oligometastatic disease, a state in which metastases are limited in number and site. Different kinds of local therapies have been used for the treatment of limited metastases and in the recent years reports on the use of Stereotactic Ablative radiotherapy (SABR) are emerging and the early results on local control are promising. Patients and methods: From October 2010 to February 2012, 76 consecutive patients for 118 lung lesions were treated. SABR was performed in case of controlled primary tumor, long-term of progression disease, exclusion of surgery, and number of metastatic sites <= 5. Different kinds of primary tumors were treated, the most common were lung and colon-rectal cancer. The total dose prescribed varied according to tumor site and maximum diameter. Dose prescription was 48 Gy in 4 fractions for peripheral lesions, 60 Gy in 8 fractions for central lesions and 60 Gy in 3 fractions for peripheral lesions with diameter <= 2 cm. Results: Dosimetric planning objectives were met for the cohort of patients with in particular V98% = 98.1 +/- 3.4% for the CTV and mean lung dose of 3.7 +/- 3.8 Gy. Radiological response was obtained in the vast majority of patients. The local control at 1, 2 and 3 years was 95%, 89% and 89% respectively. No major pulmonary toxicity, chest pain or rib fracture occurred. The median follow up was 20 months (range 6-45 months). Overall Survival (OS) at 1, 2 and 3 years was 84.1%, 73% and 73% respectively. Conclusions: SABR is feasible with limited morbidity and promising results in terms of local contro, survival and toxicity.