Non-small cell lung cancer (NSCLC) is often accompanied by brain metastasis (BM), and the prognosis of patients with BM is poor. This study assesses the prognostic impact of BM in NSCLC patients with epidermal growth factor receptor (EGFR) mutations.

We retrospectively evaluated 692 advanced NSCLC patients with EGFR mutations treated with tyrosine kinase inhibitors (TKIs) at West China Hospital from 2015 to 2019. The overall survival rate (OS), progression-free survival rate (PFS), objective response rate (ORR), disease control rate (DCR), and clinical parameters of the BM and non-BM groups were compared. Univariable and multivariable regressions were performed to identify independent prognostic factors, followed by validation of a predictive nomogram using receiver operating characteristics and calibration curves. Immune infiltration in tumor tissues was assessed by immunostaining.

NSCLC patients with BM exhibited a higher frequency of other-site and multi-organ metastases than those without BM. The BM group demonstrated significantly worse OS (26.2 vs. 39.1 months, p < 0.001) and PFS (12.3 vs. 18.8 months, p < 0.001), although the DCR (p = 0.831) and ORR (p = 0.653) were similar in both groups. BM was identified as an independent predictor of poor prognosis. The nomogram performed well, achieving a C index of 0.73, with consistent calibration curves for predicted and actual prognoses. Additionally, fewer peripheral lymphocytes were observed in the BM group.

BM is a significant risk factor for NSCLC patients, potentially linked to lymphocytopenia.