Purpose: The impact of epidermal growth factor receptor (EGFR) mutations on radiotherapy for brain metastases (BM) is undetermined. We evaluated the effects of EGFR mutation status on responses and outcomes in non-small cell lung cancer (NSCLC) patients with BM, treated with upfront or salvage stereotactic radiosurgery (SRS).
Methods and materials: From 2008 to 2015, 147 eligible NSCLC patients with 300 lesions were retrospectively analyzed. Patterns of tyrosine kinase inhibitor (TKI) therapy were recorded. Radiographic response was assessed. Brain progression-free survival (BPFS) and overall survival were calculated and outcome prognostic factors were evaluated.
Results: Median follow-up time was 13.5 months. Of the EGFR-genotyped patients, 79 (65%) were EGFR mutants, and 42 (35%) were wild type. Presence of EGFR mutations was associated with higher radiographic complete response rates (CRR). Median time to develop new BM after SRS was significantly longer for mutant-EGFR patients (17 versus 10.5 months, p = 0.02), predominantly for those with adjuvant TKI therapy (26.3 versus 15 months, p = 0.01). EGFR mutations independently predicted better BPFS (HR = 0.55, p = 0.048) in multivariate analysis.
Conclusions: In patients with NSCLC treated with SRS for BM, the presence of EGFR mutations is associated with a higher CRR, longer time for distant brain control, and better BPFS. The combination of SRS and TKI in selective patient group can be an effective treatment choice for BM with favorable brain control and little neurotoxicity.
Keywords: Brain metastases; EGFR mutation; Non-small cell lung cancer; Stereotactic radiosurgery.
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