Value of Surgical Resection in Patients with Newly Diagnosed Grade III Glioma Treated in a Multimodal Approach: Surgery, Chemotherapy and Radiotherapy

Background: Current treatments in grade III gliomas include surgery, radiotherapy, and chemotherapy. The value of the entity of surgical resection remains an open question. The aim of this evaluation was to analyze the impact of extent of resection (EOR) and residual tumor volume (RTV) on progression-free survival (PFS) and overall survival (OS) in patients with newly diagnosed grade III gliomas. Methods: Overall, 136 patients were included in this evaluation. EOR and RTV were defined in all patients on postoperative volumetric magnetic resonance imaging, with EOR being defined as the rate of surgical resection, and RTV as contrast-enhancing RTV (CE-RTV) and fluid-attenuated inversion recovery (FLAIR) RTV. A threshold of EOR and RTV was recorded using increments of 2 % and 1 cm3. Results: EOR and RTV were the only clinical variables influencing PFS and OS. The EOR cut-off value for conditioning survival was 76 %. For EOR ≥76 % or <76 %, the 5- to 10-year PFS was 57 % and 18 % versus 0 % (p = 0.03), and 5- to 10-year OS was 68 % and 42 % versus 0 % (p = 0.06), respectively. Additionally, the RTV cut-off value was 3 cm3; for RTV <3 cm3 or >3 cm3, 5- to 10-year PFS was 64.3 % and 48.2 % versus 42 % and 0 % (p = 0.02), and 5- to 10-year OS was 66.8 % and 33.4 % versus 56 % and 0 % (p = 0.3), respectively. RTV was a more significant parameter conditioning PFS and OS than EOR (p = 0.04), and the presence of CE-RTV was an unfavorable prognostic factor compared with FLAIR-RTV. Conclusions: In heterogeneous lesions from a radiological point of view as WHO grade III gliomas if a complete removal is not possible, it would be advisable to maximize the removal of enhancing areas, possibly with an EOR >76 % and an RTV <3 cm3.