P3.08-13 Stereotactic Body Radiotherapy (SBRT) for Oligometastatic Lung Nodules: A Single Institution Series

Abstract

Lung metastases from a primary extrapulmonary malignancy often represent widespread metastatic disease. There are circumstances, however, where disease may truly be limited. For patients that cannot undergo surgical metastatectomy, SBRT represents a non-invasive option. Herein, we report the results of using lung SBRT to treat limited lung lesions from extrapulmonary malignancies. We retrospectively reviewed outcomes in 44 patients with 50 lung nodules treated with SBRT. Fifty percent of the patients were male and median age was 64 (38-86). The median number of nodules was 1 (1-3) and almost all patients had oligometastatic disease (90%). Thirty-four percent of patients had extrathoracic disease. Primary malignancies included bladder (2%), breast (14%), endometrial (7%), Ewings sarcoma (2%), cholangiocarcinoma (2%), colon cancer (30%), rectal cancer (20%), small bowel (2%), head and neck (14%), renal cell (5%), and thyroid (2%). Seventy-five percent of patients had systemic therapy prior to any lung SBRT. As above, 50 lung nodules were treated with SBRT in 44 patients. Median dose was 48 Gy (36-54 Gy) in 5 fractions (3-8). This dosing scheme yielded a median BED10 of 100 Gy (60-105.6 Gy). Follow up imaging was available for review in 96% of nodules. Median follow up from SBRT was 17.5 months (1-68). One year local control was 82%. BED10>72Gy predicted improved local control (90% vs 57% at 1 year). Local control was inversely related to SUV on pre treatment PET/CT using a cut off of 4. If lesions had SUV>4.0 local control was 67% compared to 92% at one year. One year overall survival from SBRT was 66%. There was no difference in OS if patients had extrathoracic disease. Forty-six percent of patients had distant failure at 6 months. There was no acute or late grade 3 or higher toxicity. Lung SBRT is an effective and safe tool for treatment of limited lung metastases. Dose selection remains important for local control, and lesions with increased SUV show higher predilection for local failure.