Low-grade glioma (LGG) is a common primary brain tumor in young adults. The infiltrative nature and frequent growth in eloquent area in brain often makes total resection impossible. Until now, no agreement has been achieved on the treatment of LGG without total resection. Post-radiation adjuvant temozolomide (TMZ) is currently the standard of care for high-grade gliomas. Radiotherapy or TMZ is recommended for the treatment of residue low-grade gliomas. However, the efficacy of combined radiotherapy with adjuvant TMZ for residue LGG remains to be defined. In this randomized controlled trial, the investigators will test the hypothesis that radiotherapy with subsequent TMZ chemotherapy is superior to improve the progression-free survival of patients with residue LGG without significant impairment to quality of life compared to radiotherapy alone.