Clinical characteristics of brain metastases from lung cancer according to histological type: Pretreatment evaluation and survival following whole-brain radiotherapy

The histological type of lung cancer in patients with brain metastases may affect response to treatment and survival. We evaluated the clinical characteristics of brain metastases from lung cancer according to histological type in 70 consecutive patients with brain metastases from histologically confirmed lung cancer, who had been previously treated with whole-brain radiotherapy (WBRT). Histological type was divided into three categories: adenocarcinoma, small-cell lung carcinoma (SCLC) and other non-small cell lung cancer (NSCLC). The number, size and maximum diameter of brain metastases, the size and maximum diameter of peritumoral edema, the ratio of tumor and peritumoral edema, the asymptomatic ratio, the tumor size reduction rate, the complete response (CR) rate, the intracranial progression-free survival (PFS) and the overall survival (OS) were also evaluated. The median survival time for all patients was 26.2 weeks. Patients with SCLC exhibited a significantly smaller edema size and maximum diameter of edema compared to patients with other NSCLC (P=0.016 and 0.010, respectively). The ratio of tumor and peritumoral edema was also significantly lower in patients with SCLC compared to that in patients with adenocarcinoma and other NSCLC (P= 0.001). Significant differences in intracranial PFS and OS between adenocarcinoma and other NSCLC were also observed (P=0.018 and 0.004, respectively). Patients with adenocarcinoma who were treated with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) following WBRT, demonstrated a significant improvement in intracranial PFS and OS (P=0.008 and 0.004, respectively). The findings presented in this study may provide useful information for the management of brain metastases. Patients with SCLC exhibit a tendency to develop peritumoral edema to a lesser extent, compared to patients with other histological tumor types. Findings in the present study suggest that patients with adenocarcinoma, particularly those treated with EGFR-TKIs, exhibit improved survival rates.