3631 - Efficacy of Third-Generation EGFR-TKIs Combined with Stereotactic Radiotherapy for Brain Metastases in Non-Small Cell Lung Cancer
Presenter(s)
H. Sun, J. Lu, D. Chen, K. Xu, W. Jiang, and J. Liang; Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China
Purpose/Objective(s): This study sought to investigate the intracranial disease control outcomes of brain stereotactic radiotherapy (SRT) combined with third-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) versus third-generation EGFR-TKIs monotherapy in patients with EGFR-mutant non-small cell lung cancer (NSCLC) complicated by brain metastases.
Materials/Methods: A retrospective analysis was performed on the clinical data of consecutive EGFR-mutant NSCLC patients with brain metastases who received third-generation EGFR-TKIs with or without brain SRT from January 2020 to June 2024. Patients were divided into the combined radiotherapy group and the EGFR-TKI monotherapy group; combined radiotherapy was defined as the administration of brain SRT during EGFR-TKI treatment and prior to the development of intracranial progressive disease. The primary end point was iPFS.
Results: A total of 125 eligible patients were enrolled, with 60 cases (48.0%) in the combined radiotherapy group. Baseline clinical characteristics were well balanced and comparable between the two groups. For the entire cohort, the median iPFS was 21.4 months, with 1-, 2-, and 3-year iPFS rates of 76.4%, 39.1%, and 21.4%, respectively. No statistically significant difference in median iPFS was noted between the combined radiotherapy group and the monotherapy group (21.4 months vs. 21.0 months, P=0.389). Stratified analysis of patients with brain metastases measuring =1 cm in maximum diameter revealed a significantly longer median iPFS in the combined radiotherapy group than in the monotherapy group (46.2 months vs. 33.1 months, P=0.031). Univariate analysis identified =5 extracranial metastatic lesions, =3 brain metastases, no prior first-generation EGFR-TKI treatment, and exon 21 mutation as significant protective prognostic factors for iPFS (all P<0.1). Multivariate Cox regression analysis confirmed that exon 21 mutation was an independent favorable prognostic factor for improved iPFS (P=0.011, risk ratio [RR]=1.759; 95% confidence interval [95%CI]: 1.140-2.715).
Conclusion: For patients with EGFR-mutant NSCLC and brain metastases with a maximum diameter=1 cm, the combination of cranial SRT and third-generation EGFR-TKIs can significantly prolong the duration of intracranial local disease control. These preliminary retrospective findings require further validation in large-sample prospective clinical studies.