Patients With Oligometastatic Disease Limited to the Chest Are Optimal Candidates for Lung Stereotactic Body Radiotherapy

Abstract

SESSION TITLE: Advancements in Lung Cancer Diagnostics and Treatment SESSION TYPE: Original Investigation Slide PRESENTED ON: Wednesday, October 26, 2016 at 08:45 AM - 10:00 AM PURPOSE: The aim of this study was to identify patients with pulmonary metastases who would be most likely to benefit from lung stereotactic body radiotherapy (SBRT). METHODS: After institutional review board approval, we retrospectively identified 92 patients with 111 pulmonary metastases from any primary site treated with SBRT at our institution between 2008 and 2015. Gross tumor volume (GTV) was non-uniformly expanded to create an internal target volume (ITV) to encompass tumor motion. A 5 mm uniform expansion of the ITV was applied to create the planning target volume (PTV). Cone beam CT was used for daily image-guidance. The most common SBRT regimen was 48 Gy/4 fractions for peripheral lesions, and 50 Gy/5 fractions for central lesions. Toxicities were recorded according to the Common Terminology Criteria for Adverse Events (CTCAE) Version 4.0. Survival curves were calculated from the time of SBRT using the Kaplan-Meier method. RESULTS: The median follow-up was 17 months (range: 3-74 months). Median PTV was 29 cm3. There were 51 men and 41 women included, with a median age of 70 years (range: 37-90). The most common primary tumors were lung (n=30), colorectal (n=14), melanoma (n=13), and head & neck (n=12). 44 patients had solitary lung lesions, 31 patients had >1 lung lesions with no extrathoracic disease, and 17 patients had additional sites of oligometastatic disease outside of the thorax. Median time to next treatment event was 18 months in patients with metastatic disease confined to the lungs versus 5 months with extrathoracic oligometastatic disease present (p=0.01). For patients with a solitary lesion, time to next treatment was 28 months. The median, 1, 2, and 3 year survival (OS) was 33 months, 79%, 68%, and 48%, respectively. There was no significant difference in OS among patients with metastatic disease confined to the lung versus patients with additional extrathoracic oligometastatic disease (OS 37 vs 25 months, respectively; p=0.093). Primary disease site was not associated with disease outcome. Local failure occurred in 8/111 lesions for a 2-year local control rate of 85%. Grade 3 pneumonitis was reported in two (2%) of patients. There was no grade 4-5 toxicity. CONCLUSIONS: This is one of the largest experiences with lung SBRT for metastatic disease. Lung SBRT provides excellent local control with acceptable toxicity. Properly selected oligometastatic patients have excellent long-term survival with the addition of SBRT into their management. Patients with oligometastatic disease confined to the lung do especially well, while patients with extrathoracic disease progress rapidly. These findings provide guidance for optimal patient selection and counseling. CLINICAL IMPLICATIONS: Patients with limited oligometastatic disease confined to the chest are the most likely to benefit from stereotactic body radiotherapy. Time to next treatment is a clinically meaningful endpoint and helps guide decision making in patients with limited oligometastatic lung disease. DISCLOSURE: The following authors have nothing to disclose: Rebecca Fega, Uma Goyal, Helen Ross, Dawn Jaroszewski, Harshita Paripati, Kosiorek Heidi, Thomas Daniels, William Rule, Steven Schild, Sujay Vora, Jonathan Ashman No Product/Research Disclosure Information