MMDA-02 TITLE:CLINICOPATHOLOGICAL CHARACTERISTICS OF PATIENTS WITH BRAIN METASTASES FROM LUNG ADENOCARCINOMA WITH MUTATED EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) IN THE RADIOTHERAPY DEPARTMENT OF THE NATIONAL ONCOLOGY INSTITUTE. YEARS 2018–2022
Rafael Arauz, Wilson BarreraAbstract
Introduction
EGFR mutations are present in 32.4% of patients with lung adenocarcinoma (LUAD). Brain metastases (BM) from EGFR-mutated LUAD represent a major therapeutic challenge and remain a leading cause of death despite multidisciplinary treatment. Osimertinib crosses the blood-brain barrier and may improve intracranial disease control. This study aimed to determine the clinicopathological characteristics of patients with BM from LUAD with and without EGFR mutations treated with whole-brain radiotherapy (WBRT), with or without osimertinib.
Methods
A retrospective study was conducted at the National Cancer Institute from 2018 to 2022, including 79 symptomatic patients with BM who received WBRT. Patients were divided into two groups: EGFR-mutated (EGFR-m; n = 28) and EGFR non-mutated (EGFR-nm; n = 51). Clinical, therapeutic, and survival variables were analyzed using Chi-square/Fisher’s exact tests and Kaplan-Meier survival analysis.
Results
Mean age was 61.2±14.2 years in EGFR-m patients and 66.4±10.1 years in EGFR-nm patients (p = 0.05). Overall, 54.4% were women, with female sex predominating in EGFR-m patients (p = 0.006). Karnofsky performance status was ≤70 in 45.6% of cases. Non-smokers were more frequent in EGFR-m patients (p < 0.005). In the EGFR-m group, the mean number of BM lesions was 3.6±2.6 (range, 1-10; p = 0.56), and 91% had extracranial disease (p = 0.06). EGFR variants included exon 19 (64%), exon 20 (11%), and exon 21 (25%). WBRT dose was 20 Gy in 58.2% and ≥30 Gy in 41.8%. Among EGFR-m patients, 68% received osimertinib before, during, or after WBRT. Median overall survival was 4.1 months (95% CI, 2.1-6.0). Survival was longer in EGFR-m patients than in EGFR-nm patients: 7.2 versus 3.1 months (log-rank p = 0.045). Osimertinib exposure was associated with improved survival: 14.8 versus 2.7 months (p < 0.05).
Conclusion
Patients with EGFR-mutated LUAD and BM were younger, predominantly female, more often non-smokers, and mainly harbored exon 19 mutations. Survival was higher in patients treated with WBRT plus osimertinib.