[Controversy in the Postoperative Treatment of Low-grade Gliomas]

The optimal treatment for low-grade gliomas remains controversial. Neurosurgery, radiotherapy, and chemotherapy are the main treatment options. Despite advances in oncology, there are still a lot of uncertainties, and the optimal sequences, combinations, and timings of these procedures have not yet been optimized. It is still unclear whether temozolomide can replace effective, but toxic PCV chemotherapy (procarbazine, lomustine, vincristine) and whether temozolomide can be used upfront alone instead of radiotherapy alone. Mature results from phase III trials (CODEL, EORTC 22033-26033) will provide answers to these questions. Correlative analyses of survival data and molecular marker findings (1p/19q codeletion, IDH1/2 mutation, and MGMT promoter methylation status) are essential. Due to slow progressive nature of the disease, all clinical trials with low-grade gliomas are complicated by the need for long-term follow-up to obtain valid mature data, which makes any new treatment procedures or developments in basic research developed during the course of closed clinical trials difficult to apply in daily clinical practice. An example is the recently published RTOG 9802 study evaluating the role of adjuvant PCV in combination with radiotherapy for the treatment of high-risk low-grade glioma patients where the recruitment of patients was initiated almost two decades ago. Health-related quality of life after treatment of patients with expected long-term survival is also very important and its maintenance is currently the focus of considerable interest.

The main objective of the present review is to summarize the results of key clinical trials and highlight controversial issues that could have an impact on future daily practice. Another aim is to discuss these issues in the light of newly established molecular markers from the new 2016 WHO Classification of Tumors of the Central Nervous System.Key words: glioma - astrocytoma - radiotherapy - temozolomide - PCV - cognition This work was supported by MH CZ - RVO (MMCI, 00209805) and by project of the Ministry of Education, Youths and Sports of the Czech Republic CEITEC 2020 (LQ1601). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 21. 2. 2017Accepted: 20. 3. 2017.