The Impact of Targetable Mutations on Clinical Outcomes of Metastatic Epidural Spinal Cord Compression in Patients With Non-Small-Cell Lung Cancer Treated With Hybrid Therapy (Surgery Followed by Stereotactic Body Radiation Therapy).

ABSTRACT

BACKGROUND: In treatment of metastatic epidural spinal cord compression (MESCC), hybrid therapy, consisting of separation surgery, followed by stereotactic body radiation therapy, has become the mainstay of treatment for radioresistant pathologies, such as non-small-cell lung cancer (NSCLC). OBJECTIVE: To evaluate clinical outcomes of MESCC secondary to NSCLC treated with hybrid therapy and to identify clinical and molecular prognostic predictors. METHODS: This is a single-center, retrospective study. Adult patients (≥18 years old) with pathologically confirmed NSCLC and spinal metastasis who were treated with hybrid therapy for high-grade MESCC or nerve root compression from 2012 to 2019 are included. Outcome variables evaluated included overall survival (OS) and progression-free survival, local tumor control in the competing risks setting, surgical and radiation complications, and clinical-genomic correlations. RESULTS: One hundred and three patients met inclusion criteria. The median OS for this cohort was 6.5 months, with progression of disease noted in 5 (5%) patients at the index tumor level requiring reoperation and/or reirradiation at a mean of 802 days after postoperative stereotactic body radiation therapy. The 2-year local control rate was 94.6% (95% CI 89.8-99.3). Epidermal growth factor receptor (EGFR) treatment-naïve patients who initiated EGFR-targeted therapy after hybrid therapy had significantly longer OS (hazard ratio 0.47, 95% CI 0.23-0.95, P = .04) even after adjusting for smoking status. The presence of EGFR exon 21 mutation was predictive of improved progression-free survival. CONCLUSION: Hybrid therapy in NSCLC resulted in 95% local control at 2 years after surgery. EGFR treatment-naïve patients initiating therapy after hybrid therapy had significantly improved survival advantage. EGFR-targeted therapy initiated before hybrid therapy did not confer survival benefit.