Guidelines recommend early surgery for low-grade gliomas once identified to bring maximum benefit. However, there are still many patients with low-grade gliomas who have been taking a wait-and-see approach because of small lesions, lack of symptoms or concerns about the risks of surgery. Since low-grade gliomas inevitably progress malignantly, for patients who are reluctant to have surgery for various reasons, it is important to intervene at the latest before or at the time of malignant progression. This requires close follow-up. What should these patients look for when they are on watch? Magnetic resonance imaging review: review at intervals of up to six months. At least for MRI plain + enhancement. Observe the tumor signal change, growth rate on each sequence. If there is suspicious progression, perfusion, Popper and methionine PET can be added to confirm. It is best to examine at the same hospital to facilitate comparison. Signal change or increased metabolism suggests possible malignant progression and further observation is not recommended. Tumor growth rate: The median growth rate of low-grade glioma is 4mm/year (2.2-5.5mm/year). Accelerated tumor growth rate is more likely to occur malignant progression, and highly suggests malignant progression when the growth rate is greater than 8mm/year. Patients with fast or increasing growth rate suggest malignant progression, and further observation is not recommended. Symptom observation: Due to brain function compensation, low-grade glioma can be asymptomatic; when tumor growth rate increases or malignant progression, focal neurological function and cognitive dysfunction can occur out of compensation. With tumor progression, seizure symptoms may appear or seizure control may become increasingly difficult. Patients who develop symptoms are not recommended for further observation.