Whole brain radiation therapy does not improve the overall survival of EGFR-mutant NSCLC patients with leptomeningeal metastasis

BACKGROUND: Leptomeningeal metastasis (LM) is a devastating and terminal complication of advanced non-small-cell lung cancer (NSCLC), especially in patients harboring epidermal growth factor receptor (EGFR) mutations. The role of whole brain radiation therapy (WBRT) in the treatment of EGFR-mutant NSCLC patients with LM is not conclusive. Therefore, we conducted a retrospective study to evaluate the therapeutic effect of WBRT in this setting. METHODS: EGFR-mutant NSCLC patients with LM, who had previously received treatment at the Shandong Cancer Hospital and Institute from July 2014 to March 2018 were reviewed retrospectively. LM was diagnosed by positive CSF cytology and/or leptomeningeal-enhanced magnetic resonance imaging (MRI). Survival was estimated using the Kaplan-Meier method. RESULTS: In total, 51 EGFR-mutated NSCLC patients with LM were eligible for analysis, subdivided into 26 in the WBRT group and 25 in the non-WBRT group. No significant differences were observed in intracranial ORR (15.4% vs. 16%, p = 0.952) and DCR (34.7% vs. 28%, p = 0.611) between the two groups. The median iPFS(LM) and OS(LM) for the entire cohort were 3.3 months (95% CI: 2.77–3.83) and 12.6 months (95% CI: 9.66–15.54), respectively. No difference in iPFS(LM) was observed between the WBRT and non-WBRT groups (median 3.9 vs. 2.8 months; HR = 0.506, p = 0.052). The median OS(LM) was 13.6 months in the WBRT group, compared with 5.7 months in the non-WBRT group (HR = 0.454, p = 0.022). Multivariate analyses of OS(LM) showed that KPS ≥ 80 at the time of LM diagnosis (HR = 0.428, 95% CI: 0.19–0.94; p = 0.034) and the administration of EGFR-TKIs (HR = 0.258, 95% CI: 0.11–0.58; p = 0.001) were independent predictors of survival, but WBRT (HR = 0.49, 95% CI: 0.24–1.01; p = 0.54) was not. Toxicities associated with WBRT or other treatment were rare. CONCLUSION: For EGFR-mutated NSCLC patients with LM, WBRT did not improve intracranial treatment response and survival statistically.