**2.2. Low grade glioma surgical options**

For grade II glioma, the recommended treatment is maximally safe resection, with or without radiotherapy followed by procarbazine, lomustine, and vincristine administration or temozolomide plus radiotherapy followed by temozolomide depending of glioma features [20]. When it comes to low grade glioma in the meta-analysis, 5-year OS was markedly increased after resection of low grade glioma, increasing from 50–70% in STR to 80–95% in GTR [7]. GTR has superiority over STR and biopsy with increased OS and PFS [6, 21, 22]. But in another large study, they did not find any difference between STR and GTR in 5-year OS [23]. The impact of STR on OS must be more clearly defined. One study has shown that in younger patients with supratentorial low grade glioma, OS after GTR at 2 and 5 years was 99 and 93%, respectively. The PFS rates at 2 and 5 years were 82 and 48%, respectively [13].

In addition to greater OS GTR for low grade gliomas, it may impact on alerting process from low grade to high grade glioma [7]. In children after GTR, low grade glioma often does not need any further therapy, with 10 years OS rates of 90% or greater, with rare tumor recurrences [24]. In a study including patients with supratotal resection of low grade glioma with 11-year mean follow up, malignant transformation to high grade glioma did not occur. In the control group of total resection, 24% of the patients had malignant transformation from low to high grade glioma (*p* = 0.037) [19]. These promising results come from a pilot study including only 16 patients with performed supratotal resection; a larger study is needed to give a more relevant overview of the behavior of lower grade glioma after supratotal resection.
