Patients with activating epidermal growth factor receptor (EGFR) mutations are highly responsive to EGFR-tyrosine kinase inhibitors (TKIs). However, it has been reported that approximately 15–30% of patients treated with EGFR-TKIs experience central nervous system (CNS) progression, and patients with EGFR mutations exhibit a higher incidence of brain metastasis than those without such mutations. | A phase II study of Osimertinib for patients with radiotherapy-naïve CNS metastasis of non-small cell lung cancer Treatment rationale and protocol design of the OCEAN study LOGIK 1603 WJOG 9116L