Effects of EGFR-TKIs combined with intracranial radiotherapy in EGFR-mutant non-small cell lung cancer patients with brain metastases: a retrospective multi-institutional analysis.

Background: Patients with non-small cell lung cancer (NSCLC) are prone to developing brain metastases (BMs), particularly those with epidermal growth factor receptor (EGFR) mutations. In clinical practice, treatment-naïve EGFR-mutant NSCLC patients with asymptomatic BMs tend to choose EGFR-tyrosine kinase inhibitors (TKIs) as first-line therapy and defer intracranial radiotherapy (RT). However, the effectiveness of upfront intracranial RT remains unclear.

Methods: This was a retrospective study including 217 patients from two institutions between January 2018 and December 2022. Clinical data of NSCLC patients with BMs who received EGFR-TKIs were collected. The patients were assigned to one of the three groups according to the therapeutic modality used: the upfront TKI + stereotactic radiosurgery (SRS) / fractionated stereotactic radiotherapy (fSRS) group (upfront TKI + SRS/fSRS ), the upfront TKI + whole-brain radiotherapy (WBRT) group (upfront TKI + WBRT) and the upfront TKI group.

Results: As of March 8, 2023, the median follow-up duration was 37.3 months (95% CI, 32.5-42.1). The median overall survival (OS) for the upfront TKI + SRS/fSRS, upfront TKI + WBRT, and upfront TKI groups were 37.8, 20.7, and 24.1 months, respectively (p = 0.015). In subgroup analysis, the upfront TKI + SRS/fSRS group demonstrated longer OS compared to the upfront TKI + WBRT and upfront TKI groups in patients treated with first or second-generation EGFR-TKIs (p = 0.021) and patients with L858R mutation (p = 0.017), whereas no survival benefit was observed in three-generation EGFR-TKIs or 19del subgroup. In the multivariable analysis, metachronous BMs, EGFR L858R mutation and nonclassic EGFR mutation were identified as independent risk factors for OS, while a DS-GPA score of 2.0-4.0 was the only independent protective factor.

Conclusions: This study demonstrated that upfront addition of SRS/fSRS to EGFR-TKIs was associated with longer OS compared to upfront WBRT or upfront TKI alone in EGFR-mutant NSCLC patients with BMs. This improvement was more significant in patients with L858R mutation and those treated with first or second-generation EGFR-TKIs. Further research with a larger sample size is warranted.