Analysis of Toxicity and Local Control for Ultra-Central Lung Tumors Undergoing Stereotactic Body Radiation Therapy

Abstract

High toxicity rates have been reported for ultra-central lung tumors undergoing stereotactic body radiation therapy (SBRT). We retrospectively analyze a cohort of patients undergoing five fraction SBRT at our institution for ultra-central tumors defined as GTV abutting the proximal bronchial tree (PBT), aorta or esophagus.All patients treated with SBRT during 2012 to 2018 at a single institution were reviewed to identify ultra-central lesions undergoing 5 fraction SBRT. Cases were identified as GTV abutting PBT, esophagus or aorta. Patients who received at least 800 cGy per fraction were included. The primary endpoint was grade 3+ adverse events attributable to SBRT, based on CTCAE 4.0. Secondary endpoints were local control (LC) and overall survival (OS). Kaplan-Meier analysis was used to estimate LC and OS.A total of 30 patients were identified (Age 39-92), 26 with GTV abutting the PBT, 2 with GTV abutting aorta and 2 with GTV abutting esophagus. Median follow up time was 12.5 months (1 - 58 months). Five fraction doses were 50 Gy (53%), 45 Gy (26.7), 42.5 Gy (10%) and 40 Gy (10%). Tumor size ranged from 0.6 to 4.9cm. Only 1 grade 5 (3.3%) Hemoptysis toxicity was reported 1 year after SBRT and 4 Grade 3+ toxicities (13.3%), including 2 radiation pneumonitis, 1 pleural effusion and 1 large cavitary lesion with 2/4 receiving 50 Gy. LC was 75.5% at 1 year, and 56.8% at 2 years. With BED > 100, 1 year LC was 92.3% and 2 year LC was 82.1%. OS was 89.1% at 1 year, 85.4% at 2 years and 65.7% at 3 years.SBRT achieves high rates of local control at 2 years in our cohort undergoing 5 fraction SBRT with BED > 100 for ultra-central lesions with acceptable grade 3 toxicities, and potential small risk of grade 5 toxicity. Five fraction SBRT remains an acceptable option for ultra-central lesions.