Fig. 4. Guideline for recurrent WHO grade II gliomas. Surgical resection is always recommended, even in the recurrence of grade II gliomas with difficulty in complete resection such as diffuse, multi-focal, or deep located lesion in order to reduce the mass effect and improve the neurological symptoms. After surgical resection, the following therapeutic options are considered: 1) systemic chemotherapy, and/or 2) reirradiation, and/or 3) enrollment of clinical trials and/or 4) supportive treatment if poor performance status. KSNO, Korean Society for Neuro-Oncology.