Complete Remission of Multiple Brain Metastases in aPatient withEGFR-Mutated Non-Small-Cell Lung CancerTreated with First-Line Osimertinib without Radiotherapy

Osimertinib has demonstrated efficacy against stable or asymptomatic central nervous system (CNS) metastases of epidermalgrowth factor receptor (EGFR) mutation-positive non-small-cell lung cancer (NSCLC) in phase 2 and 3 clinical trials thatallowed prior CNS radiotherapy. However, the efficacy of osimertinib only or the optimal treatment combination or sequence ofradiotherapy has not been investigated. A 74-year-old woman diagnosed with T4N1M1c Stage IVB lung adenocarcinoma withEGFRmutation presented with a left upper lobe mass and multiple bilateral lung metastases. A total of more than 20asymptomatic multiple brain metastases with a maximum diameter of 12 mm were diagnosed simultaneously. Osimertinib wasadministered asfirst-line treatment. Whole brain radiotherapy was deferred because she had no neurological symptoms. After 5weeks, the multiple brain metastases disappeared completely, together with the response in the lung lesions. This casedemonstrated thatfirst-line treatment with osimertinib could even achieve complete remission of multiple brain metastasescomprising as many as twenty lesions ofEGFR-mutated NSCLC without radiation therapy. Radiation therapy for brainmetastases can be deferred or even withheld. A new treatment strategy forEGFRmutated NSCLC with CNS metastases shouldbe investigated using osimertinib, especially regarding optimal combination or sequence of radiotherapy.