Radiotherapy effects on brain/bone metastatic adenocarcinoma lung cancer and the importance of EGFR mutation test

Abstract

This study proposed to retrospectively analyze the efficacy of radiotherapy on brain/bone metastases in patients with stage IV lung adenocarcinoma and to evaluate the correlation between overall survival after radiotherapy and other factors including metastatic sites and EGFR mutation status. 115 patients with Stage IV lung adenocarcinoma admitted to our center from March, 2011 to December, 2013 were enrolled. They presented with metastases to no other solid organs except the bone or brain and had received no prior treatment. 50 patients received EGFR mutation test with 32 detected as EGFR mutant and 18 wild-type. Patients with brain metastases were treated with 40 Gy whole brain irradiation (WBI) in 2 Gy fractions; patients with bone metastases were treated with 30 Gy local irradiation in 3 Gy fractions or 40 Gy in 2 Gy fractions. All the patients received systemic therapy during or after radiotherapy and 68 received targeted therapy.The median overall survival of patients with solitary brain metastases, solitary bone metastases or combined brain and bone metastases were 8.50 months, 8.50 months and 9.50 months respectively, revealing no significant difference (p=0.57). The median overall survival of patients with EGFR mutations was 10.25 months, longer than the 8.75 months of patients without EGFR mutations, revealing no significant difference (p=0.57). The median overall survival of EGFR mutant patients with solitary bone metastases, solitary brain metastases or combined brain and bone metastases were 7.50 months, 10.50 months and 11.50 months respectively, revealing no significant difference (p=0.91). 36 patients with untested EGFR mutation status received EGFR-TKI. Among EGFR mutant patients, 10 didn't receive targeted therapy; 8 were administered Erlotinib and 14 Gefitinib with median overall survival of 10.25 months and 14.5 months, showing no significant difference (p=0.11) between the two drugs. When patients with stage IV lung adenocarcinoma have been treated by early radiotherapy, the overall survival doesn't correlate with metastatic sites. Radiotherapy could extend survival for EGFR mutant patients with stage IV lung adenocarcinoma. EGFR mutation test should be performed before treatment of the disease.

Keywords: EGFR mutations.; lung adenocarcinoma; metastases; radiotherapy.