Fig. 4. Guideline for recurrent glioblastoma. Surgical resection is always recommended if feasible. Even in surgically unresectable diseases such as diffuse, multi-focal, and deep located lesions, surgical treatment can be considered to reduce the mass effect and improve neurological symptoms. After surgical resection, the following therapeutic options are considered: systemic chemotherapy, and/or reirradiation, and/or supportive treatment if poor performance status, and/or enrollment of clinical trials. KSNO, Korean Society for Neuro-Oncology.