Stereotactic Body Radiotherapy for 186 Patients with Inoperable Lung Metastases

Abstract

This study was conducted to evaluate the efficacy and safety of stereotactic body radiotherapy (SBRT) for inoperable lung metastases(LMs). From March 2007 to May 2018, 186 patients (pts) (male: female= 118: 68) with 306 inoperable LMs were enrolled. The median age was 58 (range: 19-85) years old and median KPS was 80. The primary tumor included lung (33.3%), colorectal (22.0%), head and neck (12.4%) and breast cancer (11.3%). 57 cases (30.7%) had extrapulmonary metastases. The median disease-free interval (DFI) from diagnosis of primary cancer to lung metastases was 17.2 months (m) (0- 193.0 m). 119 cases (64.0%) received prior chemotherapy, 19 cases (10.2%) surgical resection and 5 cases (2.7%) Radiofrequency Ablation. 117 pts had single LM , and 12 pts had more than 4 LMs. The median volume of GTV and PTV were 5.0 ml (0.2 ml- 142.3 ml) and 12.0 ml (1.0 ml- 200.1 ml), respectively. The proportions of pts who received Intensity Modulated Radiation Therapy (IMRT), Volumetric Modulated Arc Therapy (VMAT) and Tomotherapy were 70.4%, 25.3% and 2.7%, respectively. Image-guided Radiation Therapy (IGRT) was used during each fraction. The main dose regimen was 60 Gy in 4 to 15 fractions. For lesions adjacent to vital structures such as hilar or large vessels, 60 Gy in 20 fractions was delivered. 82 large volume lesions were contracted 3 mm to be boost regions with simultaneously boost to 70- 80Gy. Median dose for PTV and BED was 60 Gy (40-70 Gy) and 96 Gy (60-140 Gy), respectively. Mean V5, V10, V20, V30 and mean dose of the whole lung were 26.0% (2.1%- 64.4%), 16.0% (1.4%- 42.0%), 8.5% (0.7%- 26.9%), 4.9% (0.5%- 18.0%), and 5.7Gy (1.2 Gy- 14.3 Gy), with median volume of 2986.3 ml (1648.2- 6786.5 ml). Survival analysis was assessed with Kaplan–Meier method. Toxicities were assessed by CTCAE version 4.0. Median follow-up time was 36.9 m. CR, PR, and SD rates were 54.8%, 40.9% and 3.8%, respectively. Median local control time and survival time were 27.6 m and 28.5 m, respectively. The 1-year, 2-year local control rate and overall survival rate were 96.0%, 92.0%, and 96.0%, 85.3%, respectively. Radiotherapy technique (p=0.027) and DFI (p=0.046) were prognostic factors for LCR, while extrapulmonary metastases was for OS (p<0.001). No Grade 3 toxicities were seen. 29 pts died of systemic failure, while other death reasons included primary tumor progression (7 pts) and brain metastases (6 pts). SBRT was an efficient and safe treatment for inoperable lung metastases, dose regimens should be adjusted appropriately considering the location and volume of lesions.