A new philosophy in surgery for diffuse low-grade glioma (DLGG): oncological and functional outcomes

Surgery for diffuse low-grade glioma (DLGG) was debated for a long time. Discrepancies in the classical literature are mainly due to the lack of objective radiological assessment of the extent of resection (EOR). Here, the goal is to review the recent data on oncological and functional outcomes.

Surgical series with calculation of EOR on postoperative MRI were reviewed.

In all modern series, a more aggressive resection predicted significant improvement in overall survival (OS) compared with a simple debulking. Especially, an extended removal of a margin beyond the MRI-defined abnormalities ("supra-total" resection) significantly increased OS by delaying malignant transformation. Furthermore, advances in intraoperative brain mapping techniques resulted in a minimization of neurological deficits.

These recent data strongly argue in favor of achieving a maximal resection of DLGG as the first therapeutic option. Biopsy should be considered only in very diffuse lesions (gliomatosis) or when a subtotal resection is not a priori possible. Thus, neurosurgeons should change their mind, by operating the brain involved by a chronic tumoral disease rather than by trying to remove a "tumor mass". The aim is not to achieve a simple "tumorectomy", but the most extensive resection of the brain invaded by DLGG, on the condition that this part of the brain is not crucial for cerebral functions. This new philosophy suggests to perform early and maximal resection according to functional (and not purely oncological or anatomical) boundaries in awake patients. This perspective is the best way to build a personalized "functional surgical neuro-oncology".