Long-Term Survival in Patients With Brain-Only Metastatic Lung Cancer Undergoing Upfront Intracranial Stereotactic Radiosurgery and Definitive Treatment to the Thoracic Primary Site

Document Type

Conference Proceeding

Publication Date

10-2023

Publication Title

International Journal of Radiation Oncology, Biology, Physics

Abstract

Purpose/Objective(s): To evaluate modern clinical outcomes for patients with brain-only metastatic lung cancer treated with intracranial stereotactic radiosurgery (SRS) with or without definitive treatment of the primary site. Materials/Methods: Patients with new diagnosis of lung cancer and synchronous brain-only metastatic disease treated with intracranial SRS were identified in a prospectively maintained, single institution database. Patients were stratified based on whether they did (Group A) or did not receive (Group B) definitive primary site treatment, defined by surgical resection or radiation therapy (RT) to a dose > 40 Gy. Patient demographics and treatment details were recorded. Intrathoracic, distant body, and intracranial progression, as well as overall survival (OS) and cancer specific survival (CSS) were recorded, with 2- and 5-y rates estimated using the Kaplan-Meier method. Univariate (UVA) and multivariate analysis (MVA) were performed to determine predictors of OS. Results: From 2008-2022, 107 patients were identified. 57 patients received definitive primary site treatment, of whom forty received upfront and seventeen received consolidative treatment at a median 9 months after diagnosis. 45 patients underwent fractionated RT to a median dose of 60 Gy (range 45-74 Gy), 9 underwent SBRT to a median dose of 50 Gy in 5 fractions (range 40-60 Gy), and 3 had lobectomy. Median follow-up was 2.7 y (A) and 1.2 y (B) (p<0.01). Median number of brain metastases was 1 (range 1-17; 82% 1-3 and 18% ≥ 4). There were no significant differences in patient age, sex, race, smoking status, histology, targetable mutations, AJCC T- or N-stage, receipt of systemic therapy, number or volume of brain metastases, neurologic deficits, or resected brain metastases between the groups. 82% (A) and 72% (B) of patients were T1-4N1-3, while 16% (A) and 24% (B) were T1-3N0. 32 (56%) patients in Group A received immunotherapy (ICI) versus 19 (38%) in Group B (p = 0.048). There were no differences in intracranial progression-free survival (PFS) (p = 0.17) or CNS-related death (p = 0.30) between groups. 2- and 5-y estimates for OS were 61.4% and 38.5% (A) versus 28.3% and 0% (B) (p = 0.002). 2- and 5-y CSS were 83.8% and 64.2% (A) versus 48.6% and 0% (B) (p = 0.002). 2- and 5-year intrathoracic PFS were 90% and 75% (A) versus 55% and 55% in (B) (p<0.01). 2- and 5-y distant body PFS were 49.3% and 32% (A) versus 17.3% and 0% (B) (p = 0.001). On UVA, definitive primary site treatment, receipt of immunotherapy, and young age were significant predictors of OS, and each of these remained significant on MVA. Conclusion: Definitive treatment to the thoracic primary site in patients with brain-only metastatic lung cancer after intracranial radiosurgery was associated with not only reduced rates of intrathoracic progression but also lower rates of distant systemic progression and improved overall and cancer-specific survival

Volume

117

Issue

2 Suppl.

First Page

e52

Comments

American Society for Radiation Oncology 65th Annual Meeting ASTRO 2023, October 1-4, 2023, San Diego, CA

DOI

10.1016/j.ijrobp.2023.06.762

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