Complete Remission of Brain Metastases in Non-Small Cell Lung Cancer Patients Harboring an EGFR Mutation Treated with Tyrosine Kinase Inhibitor without Radiotherapy: A Report of 3 Cases

Brain parenchymal metastasis from a solid tumor is a serious clinical condition associated with a poor outcome because systemic chemotherapy is usually ineffective for treating brain metastases (BM) due to the blood-brain barrier. Therefore, radiotherapy such as whole brain radiotherapy (WBRT) and stereotactic radiosurgery have taken on a central role in the management of BM. However, WBRT can delay subsequent systemic treatment or cause neurologic complications such as a decline in cognitive function. Therefore, suspending WBRT is worth considering if there is an effective alternative. Although there have been no large prospective studies, many reports are available about the favorable effect of tyrosine kinase inhibitors (TKIs) for treating BM in patients with non-small cell lung cancer (NSCLC). Here, we report 3 NSCLC cases that showed a complete response in BM after TKI treatment without WBRT. Based on these remarkable response rates of BM to a TKI, the potential toxicity of WBRT can be avoided, particularly in patients with small metastatic nodules and an epidermal growth factor receptor activating mutation.